91 results on '"Lian-Hui Zhang"'
Search Results
2. Regulation of Burkholderia cenocepacia virulence by the fatty acyl-CoA ligase DsfR as a response regulator of quorum sensing signal
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Xia Li, Shihao Song, Xiaohan Kong, Xiayu Chen, Zhuoxian Zhao, Zizi Lin, Yantao Jia, Yong Zhang, Hai-Bin Luo, Qiao-Ping Wang, Lian-Hui Zhang, Wei Qian, and Yinyue Deng
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CP: Microbiology ,CP: Molecular biology ,Biology (General) ,QH301-705.5 - Abstract
Summary: Quorum sensing (QS) is a cell-to-cell communication mechanism mediated by small diffusible signaling molecules. Previous studies showed that RpfR controls Burkholderia cenocepacia virulence as a cis-2-dodecenoic acid (BDSF) QS signal receptor. Here, we report that the fatty acyl-CoA ligase DsfR (BCAM2136), which efficiently catalyzes in vitro synthesis of lauryl-CoA and oleoyl-CoA from lauric acid and oleic acid, respectively, acts as a global transcriptional regulator to control B. cenocepacia virulence by sensing BDSF. We show that BDSF binds to DsfR with high affinity and enhances the binding of DsfR to the promoter DNA regions of target genes. Furthermore, we demonstrate that the homolog of DsfR in B. lata, RS02960, binds to the target gene promoter, and perception of BDSF enhances the binding activity of RS02960. Together, these results provide insights into the evolved unusual functions of DsfR that control bacterial virulence as a response regulator of QS signal.
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- 2024
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3. Regulation of the physiology and virulence of Ralstonia solanacearum by the second messenger 2′,3′-cyclic guanosine monophosphate
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Xia Li, Wenfang Yin, Junjie Desmond Lin, Yong Zhang, Quan Guo, Gerun Wang, Xiayu Chen, Binbin Cui, Mingfang Wang, Min Chen, Peng Li, Ya-Wen He, Wei Qian, Haibin Luo, Lian-Hui Zhang, Xue-Wei Liu, Shihao Song, and Yinyue Deng
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Science - Abstract
Abstract Previous studies have demonstrated that bis-(3',5')-cyclic diguanosine monophosphate (bis-3',5'-c-di-GMP) is a ubiquitous second messenger employed by bacteria. Here, we report that 2',3'-cyclic guanosine monophosphate (2',3'-cGMP) controls the important biological functions, quorum sensing (QS) signaling systems and virulence in Ralstonia solanacearum through the transcriptional regulator RSp0980. This signal specifically binds to RSp0980 with high affinity and thus abolishes the interaction between RSp0980 and the promoters of target genes. In-frame deletion of RSp0334, which contains an evolved GGDEF domain with a LLARLGGDQF motif required to catalyze 2',3'-cGMP to (2',5')(3',5')-cyclic diguanosine monophosphate (2',3'-c-di-GMP), altered the abovementioned important phenotypes through increasing the intracellular 2',3'-cGMP levels. Furthermore, we found that 2',3'-cGMP, its receptor and the evolved GGDEF domain with a LLARLGGDEF motif also exist in the human pathogen Salmonella typhimurium. Together, our work provides insights into the unusual function of the GGDEF domain of RSp0334 and the special regulatory mechanism of 2',3'-cGMP signal in bacteria.
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- 2023
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4. Pseudomonas chlororaphis L5 and Enterobacter asburiae L95 biocontrol Dickeya soft rot diseases by quenching virulence factor modulating quorum sensing signal
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Fan Liu, Ming Hu, Xu Tan, Yang Xue, Chuhao Li, Si Wang, Mingfa Lv, Xiaoyuan Chen, Xiaofan Zhou, Lian‐hui Zhang, and Jianuan Zhou
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Biotechnology ,TP248.13-248.65 - Abstract
Abstract Virulence factor modulating (VFM) is a quorum sensing (QS) signal shared by and specific to Dickeya bacteria, regulating the production of plant cell wall degrading enzymes (PCWDEs) and virulence of Dickeya. High polarity and trace of VFM signal increase the difficulty of signal separation and structure identification, and thus limit the development of quorum quenching strategy to biocontrol bacterial soft rot diseases caused by Dickeya. In order to high‐throughput screen VFM quenching bacteria, a vfmE‐gfp biosensor VR2 (VFM Reporter) sensitive to VFM signal was first constructed. Subsequently, two bacterial strains with high quenching efficiency were screened out by fluorescence intensity measurement and identified as Pseudomonas chlororaphis L5 and Enterobacter asburiae L95 using multilocus sequence analysis (MLSA). L5 and L95 supernatants reduced the expression of vfm genes, and both strains also decreased the production of PCWDEs of D. zeae MS2 and significantly reduced the virulence of D. oryzae EC1 on rice seedlings, D. zeae MS2 on banana seedlings, D. dadantii 3937 on potato and D. fangzhongdai CL3 on taro. Findings in this study provide a method to high‐throughput screen VFM quenching bacteria and characterize novel functions of P. chlororaphis and E. asburiae in biocontrolling plant diseases through quenching VFM QS signal.
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- 2023
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5. Polyamine signaling communications play a key role in regulating the pathogenicity of Dickeya fangzhongdai
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Congcong Xie, Weihan Gu, Zhongqiao Chen, Zhibin Liang, Shufen Huang, Lian-Hui Zhang, and Shaohua Chen
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Dickeya fangzhongdai ,polyamines ,bacterial motility ,plant cell wall-degrading enzymes ,pathogenicity ,Microbiology ,QR1-502 - Abstract
ABSTRACT Dickeya fangzhongdai is a devastating bacterial pathogen infecting a wide range of crops and ornamental plants worldwide. As a newly identified bacterial species in 2016, the regulatory mechanisms that govern its virulence are still a mystery. In this study, we explored the potential roles of polyamine-mediated cell-to-cell communication in regulation of D. fangzhongdai virulence. Null mutation of speA and speC in D. fangzhongdai strain ZXC1, which encodes polyamine biosynthesis through arginine and ornithine pathways, respectively, dramatically reduced bacterial motility, decreased production of plant cell wall degradation (PCWD) enzymes, and attenuated the bacterial virulence on taro and potato. We then tested the effect of various polyamine molecules in the restoration of the mutant phenotypes and showed that putrescine was the most potent signal in the regulation of virulence traits in strain ZXC1. In addition, we found that taro extract contained active signals to rescue putrescine-deficient phenotypes. High-performance liquid chromatography mass spectrometry analysis validated the speA was essential for production of putrescine in D. fangzhongdai ZXC1. We further showed that the putrescine transporters PotF and PlaP are required for putrescine-mediated cell-to-cell communication and virulence against taro and potato tubers. quantitative reverse transcription-PCR analysis demonstrated that putrescine influences the pathogenicity of D. fangzhongdai ZXC1 by regulating the expression of PCWD enzymes, bacterial chemotaxis, and flagellar-related genes. The findings from this study shed a new light for elucidating the pathogenic mechanisms of D. fangzhongdai and present useful clues for developing relevant disease control strategies. IMPORTANCE Dickeya fangzhongdai is a newly identified plant bacterial pathogen with a wide host range. A clear understanding of the cell-to-cell communication systems that modulate the bacterial virulence is of key importance for elucidating its pathogenic mechanisms and for disease control. In this study, we present evidence that putrescine molecules from the pathogen and host plants play an essential role in regulating the bacterial virulence. The significance of this study is in (i) demonstrating that putrescine signaling system regulates D. fangzhongdai virulence mainly through modulating the bacterial motility and production of PCWD enzymes, (ii) outlining the signaling and regulatory mechanisms with which putrescine signaling system modulates the above virulence traits, and (iii) validating that D. fangzhongdai could use both arginine and ornithine pathways to synthesize putrescine signals. To our knowledge, this is the first report to show that putrescine signaling system plays a key role in modulating the pathogenicity of D. fangzhongdai.
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- 2023
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6. Gram-negative bacteria resist antimicrobial agents by a DzrR-mediated envelope stress response
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Zhibin Liang, Qiqi Lin, Qingwei Wang, Luhao Huang, Huidi Liu, Zurong Shi, Zining Cui, Xiaofan Zhou, Yong-Gui Gao, Jianuan Zhou, Lian-Hui Zhang, and Yizhen Deng
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Burkholderia ,Chlorhexidine ,Dickeya ,Envelope stress response ,RND efflux pump ,Zeamine ,Biology (General) ,QH301-705.5 - Abstract
Abstract Background Envelope stress responses (ESRs) are critical for adaptive resistance of Gram-negative bacteria to envelope-targeting antimicrobial agents. However, ESRs are poorly defined in a large number of well-known plant and human pathogens. Dickeya oryzae can withstand a high level of self-produced envelope-targeting antimicrobial agents zeamines through a zeamine-stimulated RND efflux pump DesABC. Here, we unraveled the mechanism of D. oryzae response to zeamines and determined the distribution and function of this novel ESR in a variety of important plant and human pathogens. Results In this study, we documented that a two-component system regulator DzrR of D. oryzae EC1 mediates ESR in the presence of envelope-targeting antimicrobial agents. DzrR was found modulating bacterial response and resistance to zeamines through inducing the expression of RND efflux pump DesABC, which is likely independent on DzrR phosphorylation. In addition, DzrR could also mediate bacterial responses to structurally divergent envelope-targeting antimicrobial agents, including chlorhexidine and chlorpromazine. Significantly, the DzrR-mediated response was independent on the five canonical ESRs. We further presented evidence that the DzrR-mediated response is conserved in the bacterial species of Dickeya, Ralstonia, and Burkholderia, showing that a distantly located DzrR homolog is the previously undetermined regulator of RND-8 efflux pump for chlorhexidine resistance in B. cenocepacia. Conclusions Taken together, the findings from this study depict a new widely distributed Gram-negative ESR mechanism and present a valid target and useful clues to combat antimicrobial resistance.
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- 2023
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7. A type I-F CRISPRi system unveils the novel role of CzcR in modulating multidrug resistance of Pseudomonas aeruginosa
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Shuzhen Chen, Huiluo Cao, Zirui Xu, Jiahui Huang, Zhiqing Liu, Ting Li, Cheng Duan, Weiyan Wu, Yongqi Wen, Lian-Hui Zhang, and Zeling Xu
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P. aeruginosa ,type I-F CRISPRi ,efflux pump ,CzcR ,antibiotic resistance ,Microbiology ,QR1-502 - Abstract
ABSTRACT Pseudomonas aeruginosa has abundant signaling systems that exquisitely control its antibiotic resistance in response to different environmental cues. Understanding the regulation of antibiotic resistance will provide important implications for precise antimicrobial interventions. However, efficient genetic tools for functional gene characterizations are sometimes not available, particularly, in clinically isolated strains. Here, we established a type I-F CRISPRi (CSYi) system for programmable gene silencing. By incorporating anti-CRISPR proteins, this system was even applicable to bacterial hosts encoding a native type I-F CRISPR-Cas system. With the newly developed gene-silencing system, we revealed that the response regulator CzcR from the zinc (Zn2+)-responsive two-component system CzcS/CzcR is a repressor of efflux pumps MexAB-OprM and MexGHI-OpmD, which inhibits the expression of both operons by directly interacting with their promoters. Repression of MexAB-OprM consequently increases the susceptibility of P. aeruginosa to multiple antibiotics such as levofloxacin and amikacin. Together, this study provided a simple approach to study gene functions, which enabled us to unveil the novel role of CzcR in modulating efflux pump genes and multidrug resistance in P. aeruginosa. IMPORTANCE P. aeruginosa is a ubiquitous opportunistic pathogen frequently causing chronic infections. In addition to being an important model organism for antibiotic-resistant research, this species is also important for understanding and exploiting CRISPR-Cas systems. In this study, we established a gene-silencing system based on the most abundant type I-F CRISPR-Cas system in this species, which can be readily employed to achieve targeted gene repression in multiple bacterial species. Using this gene-silencing system, the physiological role of Zn2+ and its responsive regulator CzcR in modulating multidrug resistance was unveiled with great convenience. This study not only displayed a new framework to expand the abundant CRISPR-Cas and anti-CRISPR systems for functional gene characterizations but also provided new insights into the regulation of multidrug resistance in P. aeruginosa and important clues for precise anti-pseudomonal therapies.
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- 2023
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8. Pseudomonas forestsoilum sp. nov. and P. tohonis biocontrol bacterial wilt by quenching 3-hydroxypalmitic acid methyl ester
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Si Wang, Ming Hu, Huilin Chen, Chuhao Li, Yang Xue, Xinyue Song, Yuqing Qi, Fan Liu, Xiaofan Zhou, Lian-hui Zhang, and Jianuan Zhou
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3-hydroxypalmitic acid methyl ester ,quorum quenching ,Ralstonia solanacearum ,bacterial wilt ,Pseudomonas ,Plant culture ,SB1-1110 - Abstract
Bacterial wilt caused by Ralstonia solanacearum ranks the second top important bacterial plant disease worldwide. It is also the most important bacterial disease threatening the healthy development of Casuarina equisetifolia protection forest. 3-hydroxypalmitic acid methyl ester (3-OH PAME) functions as an important quorum sensing (QS) signal regulating the expression of virulence genes in R. solanacearum, and has been regarded as an ideal target for disease prevention and control. To screen native microorganisms capable of degrading 3-OH PAME, samples of C. equisetifolia branches and forest soil were collected and cultured in the medium containing 3-OH PAME as the sole carbon source. Bacteria with over 85% degradation rates of 3-OH PAME after 7-day incubation were further separated and purified. As a result, strain Q1-7 isolated from forest soil and strain Q4-3 isolated from C. equisetifolia branches were obtained and identified as Pseudomonas novel species Pseudomonas forestsoilum sp. nov. and P. tohonis, respectively, according to whole genome sequencing results. The degradation efficiencies of 3-OH PAME of strains Q1-7 and Q4-3 were 95.80% and 100.00% at 48 h, respectively. Both strains showed high esterase activities and inhibited R. solanacearum exopolysaccharide (EPS) and cellulase production. Application of strains Q1-7 and Q4-3 effectively protects C. equisetifolia, peanut and tomato plants from infection by R. solanacearum. Findings in this study provide potential resources for the prevention and control of bacterial wilt caused by R. solanacearum, as well as valuable materials for the identification of downstream quenching genes and the research and development of quenching enzymes for disease control.
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- 2023
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9. FlgI Is a Sec-Dependent Effector of Candidatus Liberibacter asiaticus That Can Be Blocked by Small Molecules Identified Using a Yeast Screen
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Siliang Zuo, Linghui Xu, Huiyan Zhang, Meiqian Jiang, Sifeng Wu, Lian-Hui Zhang, Xiaofan Zhou, and Junxia Wang
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citrus huanglongbing ,Candidatus Liberibacter asiaticus ,sec-dependent effector ,Saccharomyces cerevisiae ,Nicotiana benthamiana ,small molecule inhibitors ,Botany ,QK1-989 - Abstract
Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas) is considered to be the main pathogen responsible for HLB. There is currently no effective practical strategy for the control of HLB. Our understanding of how pathogens cause HLB is limited because CLas has not been artificially cultured. In this study, 15 potential virulence factors were predicted from the proteome of CLas through DeepVF and PHI-base searches. One among them, FlgI, was found to inhibit yeast growth when expressed in Saccharomyces cerevisiae. The expression of the signal peptide of FlgI fused with PhoA in Escherichia coli resulted in the discovery that FlgI was a novel Sec-dependent secretory protein. We further found that the carboxyl-terminal HA-tagged FlgI was secreted via outer membrane vesicles in Sinorhizobium meliloti. Fluoresence localization of transient expression FlgI-GFP in Nicotiana benthamiana revealed that FlgI is mainly localized in the cytoplasm, cell periphery, and nuclear periphery of tobacco cells. In addition, our experimental results suggest that FlgI has a strong ability to induce callose deposition and cell necrosis in N. benthamiana. Finally, by screening a large library of compounds in a high-throughput format, we found that cyclosporin A restored the growth of FlgI-expressing yeast. These results confirm that FlgI is a novel Sec-dependent effector, enriching our understanding of CLas pathogenicity and helping to develop new and more effective strategies to manage HLB.
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- 2024
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10. The GacA-GacS Type Two-Component System Modulates the Pathogenicity of Dickeya oryzae EC1 Mainly by Regulating the Production of Zeamines
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Yufan Chen, Yanchang Li, Minya Zhu, Mingfa Lv, Zhiqing Liu, Zhongqiao Chen, Ying Huang, Weihan Gu, Zhibin Liang, Changqing Chang, Jianuan Zhou, Lian-Hui Zhang, and Qiongguang Liu
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Dickeya oryzae EC1 ,GacA-GacS ,regulation network ,two-component system ,zeamines ,Microbiology ,QR1-502 ,Botany ,QK1-989 - Abstract
The GacS-GacA type two-component system (TCS) positively regulates pathogenicity-related phenotypes in many plant pathogens. In addition, Dickeya oryzae EC1, the causative agent of soft rot disease, produces antibiotic‐like toxins called zeamines as one of the major virulence factors that inhibit the germination of rice seeds. The present study identified a GacS-GacA type TCS, named TzpS-TzpA, that positively controls the virulence of EC1, mainly by regulating production of the toxin zeamines. RNA-seq analysis of strain EC1 and its tzpA mutant showed that the TCS regulated a wide range of virulence genes, especially those encoding zeamines. Protein-protein interaction was detected between TzpS and TzpA through the bacterial two-hybrid system and pull-down assay. In trans expression of tzpA failed to rescue the defective phenotypes in both the ΔtzpS and ΔtzpSΔtzpA mutants. Furthermore, TzpA controls target gene expression by direct binding to DNA promoters that contain a Gac-box motif, including a regulatory RNA rsmB and the vfm quorum-sensing system regulator vfmE. These findings therefore suggested that the EC1 TzpS-TzpA TCS system mediates the pathogenicity of Dickeya oryzae EC1 mainly by regulating the production of zeamines.[Graphic: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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- 2022
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11. RdmA Is a Key Regulator in Autoinduction of DSF Quorum Quenching in Pseudomonas nitroreducens HS-18
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Huishan Wang, Lingling Dong, Wenting Wu, Haowei Hu, Lian-Hui Zhang, and Lisheng Liao
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DSF ,quorum quenching ,autoinduction ,transcriptional repressor ,regulatory mechanism ,Microbiology ,QR1-502 - Abstract
ABSTRACT Diffusible signal factor (DSF) represents a family of widely conserved quorum-sensing (QS) signals which regulate virulence factor production and pathogenicity in numerous Gram-negative bacterial pathogens. We recently reported the identification of a highly potent DSF-quenching bacterial isolate, Pseudomonas nitroreducens HS-18, which contains an operon with four DSF-inducible genes, digABCD, or digA–D, that are responsible for degradation of DSF signals. However, the regulatory mechanisms that govern the digA–D response to DSF induction have not yet been characterized. In this study, we identified a novel transcriptional regulator we designated RdmA (regulator of DSF metabolism) which negatively regulates the expression of digA–D and represses DSF degradation. In addition, we found that a gene cluster located adjacent to rdmA was also negatively regulated by RdmA and played a key role in DSF degradation; this cluster was hence named dmg (DSF metabolism genes). An electrophoretic mobility shift assay and genetic analysis showed that RdmA represses the transcriptional expression of the dmg genes in a direct manner. Further studies demonstrated that DSF acts as an antagonist and binds to RdmA, which abrogates RdmA binding to the target promoter and its suppression on transcriptional expression of the dmg genes. Taken together, the results from this study have unveiled a central regulator and a gene cluster associated with the autoinduction of DSF degradation in P. nitroreducens HS-18, and this will aid in the understanding of the genetic basis and regulatory mechanisms that govern the quorum-quenching activity of this potent biocontrol agent. IMPORTANCE DSF family quorum-sensing (QS) signals play important roles in regulation of bacterial physiology and virulence in a wide range of plant and human bacterial pathogens. Quorum quenching (QQ), which acts by either degrading QS signals or blocking QS communication, has proven to be a potent disease control strategy, but QQ mechanisms that target DSF family signals and associated regulatory mechanisms remain largely unknown. Recently, we identified four autoinduced DSF degradation genes (digABCD) in P. nitroreducens HS-18. By using a combination of transcriptome and genetic analysis, we identified a central regulator that plays a key role in autoinduction of dig expression, as well as a new gene cluster (dmgABCDEFGH) involved in DSF degradation. The significance of our study is in unveiling the autoinduction mechanism that governs DSF signal quorum quenching for the first time, to our knowledge, and in identification of new genes and enzymes responsible for DSF degradation. The findings from this study shed new light on our understanding of the DSF metabolism pathway and the regulatory mechanisms that modulate DSF quorum quenching and will provide useful clues for design and development of a new generation of highly potent QQ biocontrol agents against DSF-mediated bacterial infections.
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- 2023
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12. Innovative microbial disease biocontrol strategies mediated by quorum quenching and their multifaceted applications: A review
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Xixian Zhu, Wen-Juan Chen, Kalpana Bhatt, Zhe Zhou, Yaohua Huang, Lian-Hui Zhang, Shaohua Chen, and Junxia Wang
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quorum quenching ,quorum sensing ,biocontrol ,acyl homoserine lactones ,diffusible signal factor ,Plant culture ,SB1-1110 - Abstract
With the increasing resistance exhibited by undesirable bacteria to traditional antibiotics, the need to discover alternative (or, at least, supplementary) treatments to combat chemically resistant bacteria is becoming urgent. Quorum sensing (QS) refers to a novel bacterial communication system for monitoring cell density and regulation of a network of gene expression that is mediated by a group of signaling molecules called autoinducers (AIs). QS-regulated multicellular behaviors include biofilm formation, horizontal gene transfer, and antibiotic synthesis, which are demonstrating increasing pathogenicity to plants and aquacultural animals as well as contamination of wastewater treatment devices. To inhibit QS-regulated microbial behaviors, the strategy of quorum quenching (QQ) has been developed. Different quorum quenchers interfere with QS through different mechanisms, such as competitively inhibiting AI perception (e.g., by QS inhibitors) and AI degradation (e.g., by QQ enzymes). In this review, we first introduce different signaling molecules, including diffusible signal factor (DSF) and acyl homoserine lactones (AHLs) for Gram-negative bacteria, AIPs for Gram-positive bacteria, and AI-2 for interspecies communication, thus demonstrating the mode of action of the QS system. We next exemplify the QQ mechanisms of various quorum quenchers, such as chemical QS inhibitors, and the physical/enzymatic degradation of QS signals. We devote special attention to AHL-degrading enzymes, which are categorized in detail according to their diverse catalytic mechanisms and enzymatic properties. In the final part, the applications and advantages of quorum quenchers (especially QQ enzymes and bacteria) are summarized in the context of agricultural/aquacultural pathogen biocontrol, membrane bioreactors for wastewater treatment, and the attenuation of human pathogenic bacteria. Taken together, we present the state-of-the-art in research considering QS and QQ, providing theoretical evidence and support for wider application of this promising environmentally friendly biocontrol strategy.
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- 2023
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13. tRNA modification enzyme MiaB connects environmental cues to activation of Pseudomonas aeruginosa type III secretion system.
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Qiqi Lin, Jiahui Huang, Zhiqing Liu, Qunyi Chen, Xinbo Wang, Guohui Yu, Ping Cheng, Lian-Hui Zhang, and Zeling Xu
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Pseudomonas aeruginosa, a major inhabitant of numerous environmental reservoirs, is a momentous opportunistic human pathogen associated with severe infections even death in the patients suffering from immune deficiencies or metabolic diseases. Type III secretion system (T3SS) employed by P. aeruginosa to inject effector proteins into host cells is one of the pivotal virulence factors pertaining to acute infections caused by this pathogen. Previous studies showed that P. aeruginosa T3SS is regulated by various environmental cues such as calcium concentration and the host signal spermidine. However, how T3SS is regulated and expressed particularly under the ever-changing environmental conditions remains largely elusive. In this study, we reported that a tRNA modification enzyme PA3980, designated as MiaB, positively regulated T3SS gene expression in P. aeruginosa and was essential for the induced cytotoxicity of human lung epithelial cells. Further genetic assays revealed that MiaB promoted T3SS gene expression by repressing the LadS-Gac/Rsm signaling pathway and through the T3SS master regulator ExsA. Interestingly, ladS, gacA, rsmY and rsmZ in the LadS-Gac/Rsm signaling pathway seemed potential targets under the independent regulation of MiaB. Moreover, expression of MiaB was found to be induced by the cAMP-dependent global regulator Vfr as well as the spermidine transporter-dependent signaling pathway and thereafter functioned to mediate their regulation on the T3SS gene expression. Together, these results revealed a novel regulatory mechanism for MiaB, with which it integrates different environmental cues to modulate T3SS gene expression in this important bacterial pathogen.
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- 2022
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14. CzcR Is Essential for Swimming Motility in Pseudomonas aeruginosa during Zinc Stress
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Zhiqing Liu, Zirui Xu, Shuzhen Chen, Jiahui Huang, Ting Li, Cheng Duan, Lian-Hui Zhang, and Zeling Xu
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Pseudomonas aeruginosa ,TCS ,CzcR ,swimming ,zinc stress ,Microbiology ,QR1-502 - Abstract
ABSTRACT Two-component system (TCS) plays a vital role in modulating target gene expression in response to the changing environments. Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that can survive under diverse stress conditions. The great adaptability of P. aeruginosa relies heavily on the abundant TCSs encoded by its genome. However, most TCSs in P. aeruginosa have not been well-characterized. CzcS/CzcR is a metal responsive TCS which displays multiple regulatory functions associated with metal hemostasis, quorum sensing activity and antibiotic resistance. In this study, we found that swimming motility of P. aeruginosa was completely abolished during zinc (Zn2+) stress when the czcR gene from the TCS CzcS/CzcR was deleted. Noticeably, CzcR was dispensable for swimming without the stress of Zn2+ excess. CzcR was shown to be activated by Zn2+ stress possibly through inducing its expression level and triggering its phosphorylation to positively regulate swimming which was abolished by Zn2+ stress in a CzcR-independent manner. Further TEM analyses and promoter activity examinations revealed that CzcR was required for the expression of genes involved in flagellar biosynthesis during Zn2+ stress. In vitro protein-DNA interaction assay showed that CzcR was capable of specifically recognizing and binding to the promoters of operons flgBCDE, flgFGHIJK, and PA1442/FliMNOPQR/flhB. Together, this study demonstrated a novel function of CzcR in regulating flagellar gene expression and motility in P. aeruginosa when the pathogen encounters Zn2+ stress conditions. IMPORTANCE The fitness of bacterial cells depends largely on their ability to sense and respond quickly to the changing environments. P. aeruginosa expresses a great number of signal sensing and transduction systems that enable the pathogen to grow and survive under diverse stress conditions and cause serious infections at different sites in many hosts. In addition to the previously characterized functions to regulate metal homeostasis, quorum sensing activity, and antibiotic resistance, here we report that CzcR is a novel regulator essential for flagellar gene expression and swimming motility in P. aeruginosa during Zn2+ stress. Since swimming motility is important for the virulence of P. aeruginosa, findings in this study might provide a new target for the treatment of P. aeruginosa infections with Zn2+-based antimicrobial agents in the future.
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- 2022
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15. A novel bacterial strain Burkholderia sp. F25 capable of degrading diffusible signal factor signal shows strong biocontrol potential
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Hongxiao Yu, Wen-Juan Chen, Kalpana Bhatt, Zhe Zhou, Xixian Zhu, Siqi Liu, Jiehua He, Lian-Hui Zhang, Shaohua Chen, Huishan Wang, and Lisheng Liao
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diffusible signal factor (DSF) ,quorum quenching ,quorum sensing ,Burkholderia ,biocontrol ,plant diseases ,Plant culture ,SB1-1110 - Abstract
Vast quantities of synthetic pesticides have been widely applied in various fields to kill plant pathogens, resulting in increased pathogen resistance and decreased effectiveness of such chemicals. In addition, the increased presence of pesticide residues affects living organisms and the environment largely on a global scale. To mitigate the impact of crop diseases more sustainably on plant health and productivity, there is a need for more safe and more eco-friendly strategies as compared to chemical prevention. Quorum sensing (QS) is an intercellular communication mechanism in a bacterial population, through which bacteria adjust their population density and behavior upon sensing the levels of signaling molecules in the environment. As an alternative, quorum quenching (QQ) is a promising new strategy for disease control, which interferes with QS by blocking intercellular communication between pathogenic bacteria to suppress the expression of disease-causing genes. Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is associated with the diffusible signal factor (DSF). As detailed in this study, a new QQ strain F25, identified as Burkholderia sp., displayed a superior ability to completely degrade 2 mM of DSF within 72 h. The main intermediate product in the biodegradation of DSF was identified as n-decanoic acid, based on gas chromatography-mass spectrometry (GC-MS). A metabolic pathway for DSF by strain F25 is proposed, based on the chemical structure of DSF and its intermediates, demonstrating the possible degradation of DSF via oxidation-reduction. The application of strain F25 and its crude enzyme as biocontrol agents significantly attenuated black rot caused by Xcc, and inhibited tissue maceration in the host plant Raphanus sativus L., without affecting the host plant. This suggests that agents produced from strain F25 and its crude enzyme have promising applications in controlling infectious diseases caused by DSF-dependent bacterial pathogens. These findings are expected to provide a new therapeutic strategy for controlling QS-mediated plant diseases.
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- 2022
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16. The virulence factor regulator and quorum sensing regulate the type I-F CRISPR-Cas mediated horizontal gene transfer in Pseudomonas aeruginosa
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Stephen Dela Ahator, Yang Liu, Jianhe Wang, and Lian-Hui Zhang
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CRISPR-Cas system ,quorum sensing ,horizontal gene transfer ,virulence factor regulator ,second messenger ,CRISPR adaptation ,Microbiology ,QR1-502 - Abstract
Pseudomonas aeruginosa is capable of thriving in diverse environments due to its network of regulatory components for effective response to stress factors. The survival of the bacteria is also dependent on the ability to discriminate between the acquisition of beneficial and non-beneficial genetic materials via horizontal gene transfer (HGT). Thus, bacteria have evolved the CRISPR-Cas adaptive immune system for defense against the deleterious effect of phage infection and HGT. By using the transposon mutagenesis approach, we identified the virulence factor regulator (Vfr) as a key regulator of the type I-F CRISPR-Cas system in P. aeruginosa. We showed that Vfr influences the expression of the CRISPR-Cas system through two signaling pathways in response to changes in calcium levels. Under calcium-rich conditions, Vfr indirectly regulates the CRISPR-Cas system via modulation of the AHL-QS gene expression, which could be vital for defense against phage infection at high cell density. When encountering calcium deficiency, however, Vfr can directly regulate the CRISPR-Cas system via a cAMP-dependent pathway. Furthermore, we provide evidence that mutation of vfr reduces the CRISPR-Cas spacer acquisition and interference of HGT. The results from this study add to the regulatory network of factors controlling the CRISPR-Cas system in response to abiotic factors in the environment. The findings may facilitate the design of effective and reliable phage therapies against P. aeruginosa infections, as targeting Vfr could prevent the development of the CRISPR-Cas mediated phage resistance.
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- 2022
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17. Genome characterization of a uropathogenic Pseudomonas aeruginosa isolate PA_HN002 with cyclic di-GMP-dependent hyper-biofilm production
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Siying Lin, Shuzhen Chen, Li Li, Huiluo Cao, Ting Li, Ming Hu, Lisheng Liao, Lian-Hui Zhang, and Zeling Xu
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Pseudomonas aeruginosa ,motility ,biofilm ,c-di-GMP ,DGC ,PDE ,Microbiology ,QR1-502 - Abstract
Pseudomonas aeruginosa can cause various types of infections and is one of the most ubiquitous antibiotic-resistant pathogens found in healthcare settings. It is capable of adapting to adverse conditions by transforming its motile lifestyle to a sessile biofilm lifestyle, which induces a steady state of chronic infection. However, mechanisms triggering the lifestyle transition of P. aeruginosa strains with clinical significance are not very clear. In this study, we reported a recently isolated uropathogenic hyper-biofilm producer PA_HN002 and characterized its genome to explore genetic factors that may promote its transition into the biofilm lifestyle. We first showed that high intracellular c-di-GMP content in PA_HN002 gave rise to its attenuated motilities and extraordinary strong biofilm. Reducing the intracellular c-di-GMP content by overexpressing phosphodiesterases (PDEs) such as BifA or W909_14950 converted the biofilm and motility phenotypes. Whole genome sequencing and comprehensive analysis of all the c-di-GMP metabolizing enzymes led to the identification of multiple mutations within PDEs. Gene expression assays further indicated that the shifted expression profile of c-di-GMP metabolizing enzymes in PA_HN002 might mainly contribute to its elevated production of intracellular c-di-GMP and enhanced biofilm formation. Moreover, mobile genetic elements which might interfere the endogenous regulatory network of c-di-GMP metabolism in PA_HN002 were analyzed. This study showed a reprogrammed expression profile of c-di-GMP metabolizing enzymes which may promote the pathoadaption of clinical P. aeruginosa into biofilm producers.
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- 2022
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18. Nutrient Availability and Phage Exposure Alter the Quorum-Sensing and CRISPR-Cas-Controlled Population Dynamics of Pseudomonas aeruginosa
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Stephen Dela Ahator, Sadhanna Sagar, Minya Zhu, Jianhe Wang, and Lian-Hui Zhang
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quorum sensing ,CRISPR-Cas system ,population dynamics ,phage infection ,Microbiology ,QR1-502 - Abstract
ABSTRACT Quorum sensing (QS) coordinates bacterial communication and cooperation essential for virulence and dominance in polymicrobial settings. QS also regulates the CRISPR-Cas system for targeted defense against parasitic genomes from phages and horizontal gene transfer. Although the QS and CRISPR-Cas systems are vital for bacterial survival, they undergo frequent selection in response to biotic and abiotic factors. Using the opportunistic Pseudomonas aeruginosa with well-established QS and CRISPR-Cas systems, we show how the social interactions between the acyl-homoserine lactone (AHL)-QS signal-blind mutants (ΔlasRrhlR) and the CRISPR-Cas mutants are affected by phage exposure and nutrient availability. We demonstrate that media conditions and phage exposure alter the resistance and relative fitness of ΔlasRrhlR and CRISPR-Cas mutants while tipping the fitness advantage in favor of the QS signal-blind mutants under nutrient-limiting conditions. We also show that the AHL signal-blind mutants are less selected by phages under QS-inducing conditions than the CRISPR-Cas mutants, whereas the mixed population of the CRISPR-Cas and AHL signal-blind mutants reduce phage infectivity, which can improve survival during phage exposure. Our data reveal that phage exposure and nutrient availability reshape the population dynamics between the ΔlasRrhlR QS mutants and CRISPR-Cas mutants, with key indications for cooperation and conflict between the strains. IMPORTANCE The increase in antimicrobial resistance has created the need for alternative interventions such as phage therapy. However, as previously observed with antimicrobial resistance, phage therapy will not be effective if bacteria evolve resistance and persist in the presence of the phages. The QS is commonly known as an arsenal for bacteria communication, virulence, and regulation of the phage defense mechanism, the CRISPR-Cas system. The QS and CRISPR-Cas systems are widespread in bacteria. However, they are known to evolve rapidly under the influence of biotic and abiotic factors in the bacterial environment, resulting in alteration in bacterial genotypes, which enhance phage resistance and fitness. We believe that adequate knowledge of the influence of environmental factors on the bacterial community lifestyle and phage defense mechanisms driven by the QS and CRISPR-Cas system is necessary for developing effective phage therapy.
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- 2022
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19. Spermidine Is an Intercellular Signal Modulating T3SS Expression in Pseudomonas aeruginosa
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Qiqi Lin, Huishan Wang, Jiahui Huang, Zhiqing Liu, Qunyi Chen, Guohui Yu, Zeling Xu, Ping Cheng, Zhibin Liang, and Lian-Hui Zhang
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spermidine ,exsCEBA ,T3SS ,regulation ,quorum sensing ,Microbiology ,QR1-502 - Abstract
ABSTRACT Pseudomonas aeruginosa is a vital opportunistic human bacterial pathogen that causes acute and chronic infections. In this study, we set to determine whether the endogenous spermidine biosynthesis plays a role in regulation of type III secretion system (T3SS). The results showed that deletion of speA and speC, which encode putrescine biosynthesis, did not seem to affect cellular spermidine level and the T3SS gene expression. In contrast, mutation of speD and speE encoding spermidine biosynthesis led to significantly decreased spermidine production and expression of T3SS genes. We also showed that endogenous spermidine could auto-induce the transcriptional expression of speE and its full functionality required the transporter SpuDEFGH. Cytotoxicity analysis showed that mutants ΔspeE and ΔspuE were substantially attenuated in virulence compared with their wild-type strain PAO1. Our data imply a possibility that spermidine biosynthesis in P. aeruginosa may not use putrescine as a substrate, and that spermidine signaling pathway may interact with other two T3SS regulatory mechanisms in certain degree, i.e., cAMP-Vfr and GacS/GacA signaling systems. Taken together, these results specify the role of endogenous spermidine in regulation of T3SS in P. aeruginosa and provide useful clues for design and development antimicrobial therapies. IMPORTANCE Type III secretion system (T3SS) is one of the pivotal virulence factors of Pseudomonas aeruginosa responsible for evading phagocytosis, and secreting and translocating effectors into host cells. Previous studies underline the complicated and elaborate regulatory mechanisms of T3SS for the accurate, fast, and malicious pathogenicity of P. aeruginosa. Among these regulatory mechanisms, our previous study indicated that the spermidine from the host was vital to the host-pathogen interaction. However, the role of endogenous spermidine synthesized by P. aeruginosa on the regulation of T3SS expression is largely unknown. Here we reveal the role and regulatory network of endogenous spermidine synthesis in regulation of T3SS and bacterial virulence, showing that the spermidine is an important interspecies signal for modulating the virulence of P. aeruginosa through regulating T3SS expression.
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- 2022
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20. PhcA and PhcR Regulate Ralsolamycin Biosynthesis Oppositely in Ralstonia solanacearum
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Peng Li, Xiulan Cao, Liwen Zhang, Mingfa Lv, and Lian-Hui Zhang
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Ralstonia solanacearum ,ralsolamycin ,PhcA ,PhcR ,regulatory mechanism ,Plant culture ,SB1-1110 - Abstract
Ralsolamycin, one of secondary metabolites in Ralstonia solanacearum, is known to be involved in crosstalk between R. solanacearum and fungi. Ralsolamycin formation is catalyzed by two-hybrid synthetases of RmyA (non-ribosomal peptide synthetase) and RmyB (polyketide synthase). A methyltransferase PhcB catalyzes formation of 3-OH MAME or 3-OH PAME, signals for the quorum sensing (QS) in R. solanacearum, while PhcB positively modulates ralsolamycin biosynthesis. A two-component system of PhcS and PhcR can response these QS signals and activate phcA expression. Here, we experimentally demonstrated that deletion of phcA (ΔphcA) substantially impaired the ralsolamycin production and expression of rmyA and rmyB in R. solanacearum strain EP1, and failed to induce chlamydospore formation of plant fungal pathogen Fusarium oxysporum f. cubense (stran FOC4). However, deletion of phcR significantly increased ralsolamycin production and expression of rmyA and rmyB, and phcR mutants exhibited enhanced ability to induce chlamydospore formation of FOC4. Results of the electrophoretic mobility shift assay suggested that both PhcA and PhcR bind to promoter of rmy operon. Taken together, these results demonstrated that both PhcA and PhcR bind to promoter of rmy operon, but regulate ralsolamycin biosynthesis in an opposite way. It could extend our knowledge on the sophisticated regulatory networks of ralsolamycin biosynthesis in R. solanacearum.
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- 2022
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21. An anthranilic acid-responsive transcriptional regulator controls the physiology and pathogenicity of Ralstonia solanacearum.
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Shihao Song, Xiuyun Sun, Quan Guo, Binbin Cui, Yu Zhu, Xia Li, Jianuan Zhou, Lian-Hui Zhang, and Yinyue Deng
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Quorum sensing (QS) is widely employed by bacterial cells to control gene expression in a cell density-dependent manner. A previous study revealed that anthranilic acid from Ralstonia solanacearum plays a vital role in regulating the physiology and pathogenicity of R. solanacearum. We reported here that anthranilic acid controls the important biological functions and virulence of R. solanacearum through the receptor protein RaaR, which contains helix-turn-helix (HTH) and LysR substrate binding (LysR_substrate) domains. RaaR regulates the same processes as anthranilic acid, and both are present in various bacterial species. In addition, anthranilic acid-deficient mutant phenotypes were rescued by in trans expression of RaaR. Intriguingly, we found that anthranilic acid binds to the LysR_substrate domain of RaaR with high affinity, induces allosteric conformational changes, and then enhances the binding of RaaR to the promoter DNA regions of target genes. These findings indicate that the components of the anthranilic acid signaling system are distinguished from those of the typical QS systems. Together, our work presents a unique and widely conserved signaling system that might be an important new type of cell-to-cell communication system in bacteria.
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- 2022
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22. Microevolution of the mexT and lasR Reinforces the Bias of Quorum Sensing System in Laboratory Strains of Pseudomonas aeruginosa PAO1
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Yang Liu, Stephen Dela Ahator, Huishan Wang, Qishun Feng, Yinuo Xu, Chuhao Li, Xiaofan Zhou, and Lian-Hui Zhang
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Pseudomonas aeruginosa PAO1 ,mexT ,lasR ,quorum sensing ,microevolution ,mexT evolution ,Microbiology ,QR1-502 - Abstract
The Pseudomonas aeruginosa strain PAO1 has routinely been used as a laboratory model for quorum sensing (QS). However, the microevolution of P. aeruginosa laboratory strains resulting in genetic and phenotypic variations have caused inconsistencies in QS research. To investigate the underlying causes of these variations, we analyzed 5 Pseudomonas aeruginosa PAO1 sublines from our laboratory using a combination of phenotypic characterization, high throughput genome sequencing, and bioinformatic analysis. The major phenotypic variations among the sublines spanned across the levels of QS signals and virulence factors such as pyocyanin and elastase. Furthermore, the sublines exhibited distinct variations in motility and biofilm formation. Most of the phenotypic variations were mapped to mutations in the lasR and mexT, which are key components of the QS circuit. By introducing these mutations in the subline PAO1-E, which is devoid of such mutations, we confirmed their influence on QS, virulence, motility, and biofilm formation. The findings further highlight a possible divergent regulatory mechanism between the LasR and MexT in the P. aeruginosa. The results of our study reveal the effects of microevolution on the reproducibility of most research data from QS studies and further highlight mexT as a key component of the QS circuit of P. aeruginosa.
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- 2022
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23. Dickeya Manipulates Multiple Quorum Sensing Systems to Control Virulence and Collective Behaviors
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Fan Liu, Ming Hu, Zhijia Zhang, Yang Xue, Shanshan Chen, Anqun Hu, Lian-hui Zhang, and Jianuan Zhou
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soft rot Pectobacteriaceae ,Dickeya ,quorum sensing ,regulation ,virulence ,Plant culture ,SB1-1110 - Abstract
Soft rot Pectobacteriaceae (SRP), typical of Pectobacterium and Dickeya, are a class of Gram-negative bacterial pathogens that cause devastating diseases on a wide range of crops and ornamental plants worldwide. Quorum sensing (QS) is a cell-cell communication mechanism regulating the expression of specific genes by releasing QS signal molecules associated with cell density, in most cases, involving in the vital process of virulence and infection. In recent years, several types of QS systems have been uncovered in Dickeya pathogens to control diverse biological behaviors, especially bacterial pathogenicity and transkingdom interactions. This review depicts an integral QS regulation network of Dickeya, elaborates in detail the regulation of specific QS system on different biological functions of the pathogens and hosts, aiming at providing a systematic overview of Dickeya pathogenicity and interactions with hosts, and, finally, expects the future prospective of effectively controlling the bacterial soft rot disease caused by Dickeya by quenching the key QS signal.
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- 2022
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24. Hfq Is a Critical Modulator of Pathogenicity of Dickeya oryzae in Rice Seeds and Potato Tubers
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Zurong Shi, Qingwei Wang, Shunchang Wang, Chengrun Wang, Lian-Hui Zhang, and Zhibin Liang
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zeamines ,biofilm ,hypersensitive response ,Biology (General) ,QH301-705.5 - Abstract
The frequent outbreaks of soft-rot diseases caused by Dickeya oryzae have emerged as severe problems in plant production in recent years and urgently require the elucidation of the virulence mechanisms of D. oryzae. Here, we report that Hfq, a conserved RNA chaperone protein in bacteria, is involved in modulating a series of virulence-related traits and bacterial virulence in D. oryzae EC1. The findings show that the null mutation of the hfqEC1 gene totally abolished the production of zeamine phytotoxins and protease, significantly attenuated the production of two other types of cell wall degrading enzymes, i.e., pectate lyase and cellulase, as well as attenuating swarming motility, biofilm formation, the development of hypersensitive response to Nicotiana benthamiana, and bacterial infections in rice seeds and potato tubers. QRT-PCR analysis and promoter reporter assay further indicated that HfqEC1 regulates zeamine production via modulating the expression of the key zeamine biosynthesis (zms) cluster genes. Taken together, these findings highlight that the Hfq of D. oryzae is one of the key regulators in modulating the production of virulence determinants and bacterial virulence in rice seeds and potato tubers.
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- 2022
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25. Engineered Sucrose Metabolism Improves the Smut Disease Suppression Potency of Pseudomonas sp. ST4
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Nuo Qiao Lin, Zhi Bin Liang, Hui Shan Wang, Xiao Yan Wu, Lian Hui Zhang, and Yi Zhen Deng
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Ecology ,Applied Microbiology and Biotechnology ,Food Science ,Biotechnology - Abstract
Sporisorium scitamineum and Ustilago maydis are typical dimorphic fungi causing severe sugarcane and maize smut diseases, respectively. Sexual mating of compatible sporidia is essential for these pathogens to form infections dikaryotic mycelia and cause smut diseases.
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- 2023
26. A Bacterial Isolate Capable of Quenching Both Diffusible Signal Factor- and N-Acylhomoserine Lactone-Family Quorum Sensing Signals Shows Much Enhanced Biocontrol Potencies
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Huishan Wang, Qiqi Lin, Lingling Dong, Wenting Wu, Zhibing Liang, Zhangyong Dong, Huijuan Ye, Lisheng Liao, and Lian-Hui Zhang
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General Chemistry ,General Agricultural and Biological Sciences - Published
- 2022
27. Cyclic di-GMP interact with putrescine via a PilZ domain receptor YcgR
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Weihan Gu, Yufan Chen, Zhongqiao Chen, Huagui Gao, Congcong Xie, Lian-hui Zhang, and Lisheng Liao
- Abstract
The cell motility is one of the key pathogenic factors that contribute to the virulence ofDickeya oryzea,which is a prevalent bacterial pathogen capable of infecting a range of crops and plants. We showed recently that the bacterial second messenger c-di-GMP, and the putrescine-mediated quorum sensing (QS) system, are both involved in the regulation of the bacterial motility inD. oryzeaEC1. In this study, we set to determine whether and how there two signaling mechanisms work together to modulate the bacterial motility. The results showed that the second messenger signaling system interacts with the putrescine QS system via the c-di-GMP receptor YcgR, which could promote the activity of SpeA, the rate-limiting enzyme in the putrescine biosynthesis pathway, thereby increasing the intracellular putrescine levels. However, it was shown that this facilitative effect could be inhibited by c-di-GMP molecules. In addition, we demonstrated the dominance of c-di-GMP over putrescine in the regulation of bacterial motility. The findings from this study provide the first insight into the interaction between c-di-GMP and putrescine in bacteria and provide a valuable reference for the study of intracellular second messenger system and polyamine-mediated quorum sensing system in other bacteria.ImportanceDickea oryzeais a major bacterial pathogen capable of infesting many plants and crops, causing significant economic damage to rice and banana production especially. Bacterial motility is a key pathogenic factor ofD. oryzeato compete for food resources and infect their host species, which is negatively regulated by c-di-GMP and positively regulated by putrescine, respectively. However, the connection between c-di-GMP and putrscine in regulating the motility ofD.oryzeais not understood. Here we revealed the link and the mechanism of interaction between them, showing that c-di-GMP interact with putrescine via a receptor of c-di-GMP. The significance of our research is in providing the first insight into the interaction between c-di-GMP and putrescine and the methods and experimental designs in our study will provide a valuable reference for subsequent studies on the link between c-di-GMP and putrescine in other bacteria and even the regulatory mechanisms of complex bacterial motility networks, respectively.
- Published
- 2023
28. Cyclic di‐GMP modulates sessile‐motile phenotypes and virulence in Dickeya oryzae via two PilZ domain receptors
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Yufan Chen, Mingfa Lv, Zhibin Liang, Zhiqing Liu, Jianuan Zhou, and Lian‐Hui Zhang
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Phenotype ,Bacterial Proteins ,Virulence ,Soil Science ,Oryza ,Gene Expression Regulation, Bacterial ,Plant Science ,Carrier Proteins ,Dickeya ,Cyclic GMP ,Agronomy and Crop Science ,Molecular Biology - Abstract
Dickeya oryzae is a bacterial pathogen causing the severe rice stem rot disease in China and other rice-growing countries. We showed recently that the universal bacterial second messenger c-di-GMP plays an important role in modulation of bacterial motility and pathogenicity, but the mechanism of regulation remains unknown. In this study, bioinformatics analysis of the D. oryzae EC1 genome led to the identification of two proteins, YcgR and BcsA, both of which contain a conserved c-di-GMP receptor domain, known as the PilZ-domain. By deleting all the genes encoding c-di-GMP-degrading enzymes in D. oryzae EC1, the resultant mutant 7ΔPDE with high c-di-GMP levels became nonmotile, formed hyperbiofilm, and lost the ability to colonize and invade rice seeds. These phenotypes were partially reversed by deletion of ycgR in the mutant 7ΔPDE, whereas deletion of bcsA only reversed the hyperbiofilm phenotype of mutant 7ΔPDE. Significantly, double deletion of ycgR and bcsA in mutant 7ΔPDE rescued its motility, biofilm formation, and virulence to levels of wild-type EC1. In vitro biochemical experiments and in vivo phenotypic assays further validated that YcgR and BcsA proteins are the receptors for c-di-GMP, which together play a critical role in regulating the c-di-GMP-associated functionality. The findings from this study fill a gap in our understanding of how c-di-GMP modulates bacterial motility and biofilm formation, and provide useful clues for further elucidation of sophisticated virulence regulatory mechanisms in this important plant pathogen.
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- 2022
29. OhrR is a central transcriptional regulator of virulence in Dickeya zeae
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Xiaofan Zhou, Yufan Chen, Lian-Hui Zhang, Sixuan Ye, Qinglin Yu, Jianuan Zhou, Ling Jinfeng, Mingfa Lv, Cheng Duan, and Ming Hu
- Subjects
Dickeya zeae ,Regulator ,Soil Science ,Virulence ,Swarming motility ,Plant Science ,Biology ,biofilm ,Bacterial Proteins ,Enterobacteriaceae ,Transcriptional regulation ,pathogenicity ,Electrophoretic mobility shift assay ,Dickeya ,Molecular Biology ,Gene ,Pathogen ,Plant Diseases ,Regulator gene ,Genetics ,c‐di‐GMP ,food and beverages ,Gene Expression Regulation, Bacterial ,Original Articles ,motility ,Original Article ,Agronomy and Crop Science ,zeamines - Abstract
Dickeya zeae is the causal agent of rice foot rot disease. The pathogen is known to rely on a range of virulence factors, including phytotoxin zeamines, extracellular enzymes, cell motility, and biofilm, which collectively contribute to the establishment of infections. Phytotoxin zeamines play a critical role in bacterial virulence; signalling pathways and regulatory mechanisms that govern bacterial virulence remain unclear. In this study, we identified a transcriptional regulator OhrR (organic hydroperoxide reductase regulator) that is involved in the regulation of zeamine production in D. zeae EC1. The OhrR null mutant was significantly attenuated in its virulence against rice seed, potato tubers and radish roots. Phenotype analysis showed that OhrR was also involved in the regulation of other virulence traits, including the production of extracellular cellulase, biofilm formation, and swimming/swarming motility. DNA electrophoretic mobility shift assay showed that OhrR directly regulates the transcription of key virulence genes and genes encoding bis‐(3′–5′)‐cyclic dimeric guanosine monophosphate synthetases. Furthermore, OhrR positively regulates the transcription of regulatory genes slyA and fis through binding to their promoter regions. Our findings identify a key regulator of the virulence of D. zeae and add new insights into the complex regulatory network that modulates the physiology and virulence of D. zeae., OhrR is crucial for regulatory of virulence factors production and pathogenicity, and regulates SlyA and Fis to control the expression of downstream virulence genes.
- Published
- 2021
30. Elongation factor P modulates
- Author
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Quan, Guo, Binbin, Cui, Mingfang, Wang, Xia, Li, Huihui, Tan, Shihao, Song, Jianuan, Zhou, Lian-Hui, Zhang, and Yinyue, Deng
- Subjects
Acinetobacter baumannii ,Bacterial Proteins ,Virulence ,Phosphoric Diester Hydrolases ,Biofilms ,Escherichia coli Proteins ,Guanosine Monophosphate ,Gene Expression Regulation, Bacterial ,Phosphorus-Oxygen Lyases ,Peptide Elongation Factors ,Cyclic GMP - Abstract
Cyclic diguanosine monophosphate (c-di-GMP) is widely used by bacteria to control biological functions in response to diverse signals or cues. A previous study showed that potential c-di-GMP metabolic enzymes play a role in the regulation of biofilm formation and motility in
- Published
- 2022
31. Nutrient Availability and Phage Exposure Alter the Quorum-Sensing and CRISPR-Cas-Controlled Population Dynamics of Pseudomonas aeruginosa.
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Ahator, Stephen Dela, Sagar, Sadhanna, Minya Zhu, Jianhe Wang, and Lian-Hui Zhang
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- 2022
- Full Text
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32. The cis -2-Dodecenoic Acid (BDSF) Quorum Sensing System in Burkholderia cenocepacia
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Mingfang Wang, Xia Li, Shihao Song, Chaoyu Cui, Lian-Hui Zhang, and Yinyue Deng
- Subjects
Ecology ,Applied Microbiology and Biotechnology ,Food Science ,Biotechnology - Abstract
It has been demonstrated that quorum sensing (QS) is widely employed by bacterial cells to coordinately regulate various group behaviors. Diffusible signal factor (DSF)-type signals have emerged as a growing family of conserved cell-cell communication signals.
- Published
- 2022
33. The Two-Component System FleS/FleR Represses H1-T6SS via Cyclic di-GMP Signaling in Pseudomonas aeruginosa
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Lian-Hui Zhang, Qiqi Lin, Jiahui Huang, Tian Zhou, Zhiqing Liu, and Zeling Xu
- Subjects
Ecology ,Virulence ,Effector ,Pseudomonas aeruginosa ,Regulator ,Genetics and Molecular Biology ,Gene Expression Regulation, Bacterial ,Biology ,Type VI Secretion Systems ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Two-component regulatory system ,Cell biology ,Transcriptome ,Bacterial Proteins ,medicine ,Humans ,Regulatory Pathway ,Transcription factor ,Cyclic GMP ,Food Science ,Biotechnology ,Type VI secretion system ,Transcription Factors - Abstract
The type VI secretion system (T6SS) is an important translocation apparatus that is widely employed by Gram-negative bacteria to deliver toxic effectors into eukaryotic and prokaryotic target cells, causing host damage and providing competitive advantages in polymicrobial environments. The genome of Pseudomonas aeruginosa harbors three T6SS clusters (H1-T6SS, H2-T6SS, H3-T6SS). Activities of these systems are tightly regulated by a complicated signaling network which remains largely elusive. In this study, we focused on a previously characterized two-component system FleS/FleR, and performed comparative transcriptome analysis between the PAO1 wild-type strain and its isogenic ΔfleR mutant, which revealed the important role of FleS/FleR in regulating multiple physiological pathways including T6SS. Gene expression and bacterial killing assays showed that the expression and activity of H1-T6SS are repressed in the wild-type strain owing to the high intracellular c-di-GMP content. Further explorations demonstrated that c-di-GMP relies on the transcription factor FleQ to repress H1-T6SS and its synthesis is controlled by a global regulator AmrZ which is induced by the active FleS/FleR. Interestingly, repression of H1-T6SS by FleS/FleR in PAO1 is independent of RetS which is known to regulate H1-T6SS by controlling the central post-transcriptional factor RsmA. Together, our results identified a novel regulator of H1-T6SS and provided detailed mechanisms of this signaling pathway in PAO1. IMPORTANCE Pseudomonas aeruginosa is an opportunistic human pathogen distributed widely in the environment. The genome of this pathogen contains three T6SS clusters which contribute significantly to its virulence. Understanding the complex regulatory network that controls the activity of T6SS is essential for the development of effective therapeutic treatments for P. aeruginosa infections. In this study, transcriptome analysis led to the identification of a novel regulator FleS/FleR which inversely regulates H1-T6SS and H2-T6SS in P. aeruginosa PAO1. We further revealed a detailed FleS/FleR-mediated regulatory pathway of H1-T6SS in PAO1 which involves two additional transcriptional regulators AmrZ and FleQ and the second messenger c-di-GMP, providing important implications to develop novel anti-infective strategies and antimicrobial drugs.
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- 2022
34. Polymorphisms of Potential Drug Resistant Molecular Markers in Plasmodium Vivax From China–Myanmar Border During 2008 to 2017
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Zhen-sheng Wang, Chun-yan Wei, Yun-chun Pan, Zhi-hua Wang, Xin Ji, Qianqian Chen, Lian-hui Zhang, Zenglei Wang, and Heng Wang
- Abstract
Background: Plasmodium vivax remains the predominant species at the China–Myanmar border, imposing a major challenge to the recent gains in regional malaria elimination. To closely supervise the emerging of drug resistance in this area, we surveyed the variations in genes potentially correlated with drug resistance in P. vivax parasite and the possible drug selection with time.Methods: A total of 235 P. vivax samples were collected from patients suffering uncomplicated malaria at Yingjiang, Tengchong, and Longling counties, and Nabang port in China, Yunnan province, and Laiza township in Myanmar, during 2008 to 2017. Five potential drug resistance genes were amplified utilizing nested-PCR and analyzed, including pvdhfr, pvdhps, pvmdr1, pvcrt-o, and pvk12. Results: The pvdhfr F57I/L, S58R, T61M and S117T/N presented in 40.64%, 56.68%, 40.11%, and 56.04% of the sequenced P. vivax isolates, and these mutations significantly decreased with years. The haplotype formed by these quadruple mutations predominated at Yingjiang, Tengchong, Longling and Nabang. While a mutation H99S/R (56.59%) dominated at Laiza and increased with time. In pvdhps, the A383G prevailed in 69.16% of the samples, which remained the most prevalent haplotype. However, a significant decrease of its occurrence was also noticed over the time. The S382A/C and A553G existed in 8.37% and 30.84% of the isolates, respectively. In pvmdr1, the mutation Y976F occurred at a low frequency in 5/232 (2.16%), while T958M was fixed and F1076L was approaching fixed (72.41%). The K10 insertion was detected at an occurrence of 33.17% in pvcrt-o, whereas there was no significant difference among the sites or over the time. No mutation was identified in pvk12.Conclusions: Mutations related with resistance to antifolate drugs are prevalent in this area as expected, while their frequencies decrease significantly with time, suggestive of increased susceptibility of P. vivax parasite to antifolate drugs. Resistance to CQ is possibly emerging. However, since the molecular mechanisms underneath CQ resistance is yet to be better understood, close supervision of clinical drug efficiency and continuous function investigation is urgently needed to alarm drug resistance.
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- 2022
35. The
- Author
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Mingfang, Wang, Xia, Li, Shihao, Song, Chaoyu, Cui, Lian-Hui, Zhang, and Yinyue, Deng
- Subjects
Fatty Acids, Monounsaturated ,Bacterial Proteins ,Burkholderia ,Burkholderia cenocepacia ,Suppressor Factors, Immunologic ,Quorum Sensing ,Gene Expression Regulation, Bacterial ,Minireview - Abstract
It has been demonstrated that quorum sensing (QS) is widely employed by bacterial cells to coordinately regulate various group behaviors. Diffusible signal factor (DSF)-type signals have emerged as a growing family of conserved cell-cell communication signals. In addition to the DSF signal initially identified in Xanthomonas campestris pv. campestris, Burkholderia diffusible signal factor (BDSF) (cis-2-dodecenoic acid) has been recognized as a conserved DSF-type signal with specific characteristics in both signal perception and transduction from DSF signals. Here, we review the history and current progress of the research on this type of signal, especially focusing on its biosynthesis, signaling pathways, and biological functions. We also discuss and explore the huge potential of targeting this kind of QS system as a new therapeutic strategy to control bacterial infections and diseases.
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- 2022
36. Microevolution of the
- Author
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Yang, Liu, Stephen Dela, Ahator, Huishan, Wang, Qishun, Feng, Yinuo, Xu, Chuhao, Li, Xiaofan, Zhou, and Lian-Hui, Zhang
- Abstract
The
- Published
- 2021
37. First Report of Pectobacterium aroidearum Causing Soft Rot in Olecranon Honey Peach (Prunus persica) in China
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Huidi Liu, Lian-Hui Zhang, Zeling Xu, and Zhibin Liang
- Subjects
Pectobacterium ,biology ,Inoculation ,Sequence analysis ,Accession number (library science) ,food and beverages ,Plant Science ,biology.organism_classification ,16S ribosomal RNA ,Housekeeping gene ,Prunus ,Horticulture ,Agronomy and Crop Science ,Fruit tree - Abstract
Olecranon honey peach (Prunus persica L.) is a popular fruit tree cultivated in Guangdong Province of China. Due to its excellent economic values and popularity, it has recently been widely adopted and planted in several other southern Provinces and Autonomous Region in China, including Yunnan, Hunan, Jiangxi, Guizhou, and Guangxi. In Lianping County of Guangdong Province alone, the annual peach fruit production was about 78,800 tonnes (Xie et al. 2017). In July 2021, peach fruits showing soft rot symptoms were collected from an olecranon honey peach plantation in Lechang, Guangdong, China. Symptoms included tissue disintegration with bacterial oozes and rotting smells. To isolate the causal agent of soft rot in the peach fruits, the bacterial oozes from various rotted fruits were streaked on the modified YEB agar plate (Huang et al. 2021), and 21 bacterial colonies were selected for PCR amplification using the primers targeting the conserved region of 16S rDNA gene (Wei et al. 2020). A blastN analysis of the DNA sequences of the obtained PCR fragments in NCBI website indicated that 17 isolates named as ZL strains were potential bacterial species of Pectobacterium with about 99% similarity (Genbank accession number of ZL1: OK189602) to Pectobacterium aroidearum SCRI 109T (Genbank accession number: NR_159926). Three of them (ZL1, ZL2 and ZL3) were selected for assay of pathogenicity. The bacterial suspensions (10 μl, 1×106 CFU/ml) of strains ZL1, ZL2 and ZL3 were injected into olecranon honey peach fruits by using a syringe. A portion of peach fruits were similarly injected with sterile distilled water as the negative control. After 18 h incubation at 25 °C, the typical symptom of soft rot, i.e., tissue decay, became visible on the peach fruits inoculated with the bacterial suspensions. After inoculation for 42 h, bacterial oozes were exuded from rotting tissues. Peach fruits without injuries were also sprayed with the bacterial suspensions under the same conditions, but decay symptoms were not observed, suggesting that the bacterial infection needs the wounding or injuries. To fulfill the Koch's postulates, bacterial colonies were re-isolated from bacterial oozes, and their conserved region of 16S rDNA fragments were amplified and sequenced. Bioinformatics analysis of the DNA sequence data confirmed that all the isolated colonies were Pectobacterium strains. Using the Biolog Gen III system, the representative strain ZL1 was identified as Pectobacterium (SIM 0.56). Transmission electron microscopy analysis showed that the bacterial cells of strain ZL1 were rod-shaped with peripheral flagella. To further determine the species of ZL strains, eight housekeeping genes (acnA, gapA, icd, mdh, mtlD, pgi, proA and rpoS) were analyzed by the methods described previously (Nabhan et al. 2013). The amplified DNA sequences analyzed by the blastN program in NCBI showed that the sequences of eight housekeeping genes from strains ZL1, ZL2 and ZL3 were identical to each other (Genbank accession number: OK274248 to OK274255), and most of the gene sequences shared over 99% similarity to their counterparts in P. aroidearum L6 (Genbank accession number: NZ_CP065044) (Xu et al. 2021), except that the acnA and proA genes showed about 98% and 96% similarity respectively to the corresponding genes of P. aroidearum L6. In addition, the multi-locus sequence analysis (MLSA) using DNA sequences of above eight housekeeping genes showed that ZL strains were grouped with other P. aroidearum strains. Taken together, the results of molecular and biochemical assays confirmed that ZL strains isolated from olecranon honey peach fruits were P. aroidearum. To our knowledge, this is the first report of P. aroidearum causing soft rot disease in olecranon honey peach in China. P. aroidearum is a relatively newly described soft rot pathogen (Nabhan et al. 2013). More recently, the pathogen was found causing soft rot infections in lettuce, Chinese cabbage, pepper (Capsicum annuum) fruits, konjac, carrot and Syngonium podophyllum (Barroso et al. 2019; Moraes et al. 2020; Sun et al. 2019; Tang et al. 2020; Xu et al. 2021). The results of this study add a new plant species to the host range of P. aroidearum.
- Published
- 2022
38. FlgI Is a Sec-Dependent Effector of Candidatus Liberibacter asiaticus That Can Be Blocked by Small Molecules Identified Using a Yeast Screen.
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Zuo, Siliang, Xu, Linghui, Zhang, Huiyan, Jiang, Meiqian, Wu, Sifeng, Zhang, Lian-Hui, Zhou, Xiaofan, and Wang, Junxia
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CANDIDATUS liberibacter asiaticus ,SMALL molecules ,EXTRACELLULAR vesicles ,CYCLOSPORINE ,NICOTIANA benthamiana ,YEAST ,SIGNAL peptides - Abstract
Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The phloem-restricted bacterium Candidatus Liberibacter asiaticus (CLas) is considered to be the main pathogen responsible for HLB. There is currently no effective practical strategy for the control of HLB. Our understanding of how pathogens cause HLB is limited because CLas has not been artificially cultured. In this study, 15 potential virulence factors were predicted from the proteome of CLas through DeepVF and PHI-base searches. One among them, FlgI, was found to inhibit yeast growth when expressed in Saccharomyces cerevisiae. The expression of the signal peptide of FlgI fused with PhoA in Escherichia coli resulted in the discovery that FlgI was a novel Sec-dependent secretory protein. We further found that the carboxyl-terminal HA-tagged FlgI was secreted via outer membrane vesicles in Sinorhizobium meliloti. Fluoresence localization of transient expression FlgI-GFP in Nicotiana benthamiana revealed that FlgI is mainly localized in the cytoplasm, cell periphery, and nuclear periphery of tobacco cells. In addition, our experimental results suggest that FlgI has a strong ability to induce callose deposition and cell necrosis in N. benthamiana. Finally, by screening a large library of compounds in a high-throughput format, we found that cyclosporin A restored the growth of FlgI-expressing yeast. These results confirm that FlgI is a novel Sec-dependent effector, enriching our understanding of CLas pathogenicity and helping to develop new and more effective strategies to manage HLB. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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39. Characterization of the Arn lipopolysaccharide modification system essential for zeamine resistance unveils its new roles in Dickeya oryzae physiology and virulence.
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Liang, Zhibin, Huang, Luhao, Liu, Huidi, Zheng, Ying, Feng, Jiani, Shi, Zurong, Chen, Yufan, Lv, Mingfa, Zhou, Jianuan, Zhang, Lian‐Hui, and Chen, Shaohua
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PYRICULARIA oryzae ,PHYSIOLOGY ,BACTERIAL enzymes ,CHINESE cabbage ,BACTERIAL physiology ,DELETION mutation ,OPERONS - Abstract
The zeamines produced by Dickeya oryzae are potent polyamine antibiotics and phytotoxins that are essential for bacterial virulence. We recently showed that the RND efflux pump DesABC in D. oryzae confers partial resistance to zeamines. To fully elucidate the bacterial self‐protection mechanisms, in this study we used transposon mutagenesis to identify the genes encoding proteins involved in zeamine resistance in D. oryzae EC1. This led to the identification of a seven‐gene operon, arnEC1, that encodes enzyme homologues associated with lipopolysaccharide modification. Deletion of the arnEC1 genes in strain EC1 compromised its zeamine resistance 8‐ to 16‐fold. Further deletion of the des gene in the arnEC1 mutant background reduced zeamine resistance to a level similar to that of the zeamine‐sensitive Escherichia coli DH5α. Intriguingly, the arnEC1 mutants showed varied bacterial virulence on rice, potato, and Chinese cabbage. Further analyses demonstrated that ArnBCATEC1 are involved in maintenance of the bacterial nonmucoid morphotype by repressing the expression of capsular polysaccharide genes and that ArnBEC1 is a bacterial virulence determinant, influencing transcriptional expression of over 650 genes and playing a key role in modulating bacterial motility and virulence. Taken together, these findings decipher a novel zeamine resistance mechanism in D. oryzae and document new roles of the Arn enzymes in modulation of bacterial physiology and virulence. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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40. Regulation of the physiology and virulence of Ralstonia solanacearum by the second messenger 2′,3′-cyclic guanosine monophosphate.
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Li, Xia, Yin, Wenfang, Lin, Junjie Desmond, Zhang, Yong, Guo, Quan, Wang, Gerun, Chen, Xiayu, Cui, Binbin, Wang, Mingfang, Chen, Min, Li, Peng, He, Ya-Wen, Qian, Wei, Luo, Haibin, Zhang, Lian-Hui, Liu, Xue-Wei, Song, Shihao, and Deng, Yinyue
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GUANYLIC acid ,RALSTONIA solanacearum ,SALMONELLA typhimurium ,QUORUM sensing ,PHYSIOLOGY ,PHENOTYPES - Abstract
Previous studies have demonstrated that bis-(3',5')-cyclic diguanosine monophosphate (bis-3',5'-c-di-GMP) is a ubiquitous second messenger employed by bacteria. Here, we report that 2',3'-cyclic guanosine monophosphate (2',3'-cGMP) controls the important biological functions, quorum sensing (QS) signaling systems and virulence in Ralstonia solanacearum through the transcriptional regulator RSp0980. This signal specifically binds to RSp0980 with high affinity and thus abolishes the interaction between RSp0980 and the promoters of target genes. In-frame deletion of RSp0334, which contains an evolved GGDEF domain with a LLARLGGDQF motif required to catalyze 2',3'-cGMP to (2',5')(3',5')-cyclic diguanosine monophosphate (2',3'-c-di-GMP), altered the abovementioned important phenotypes through increasing the intracellular 2',3'-cGMP levels. Furthermore, we found that 2',3'-cGMP, its receptor and the evolved GGDEF domain with a LLARLGGDEF motif also exist in the human pathogen Salmonella typhimurium. Together, our work provides insights into the unusual function of the GGDEF domain of RSp0334 and the special regulatory mechanism of 2',3'-cGMP signal in bacteria. Nucleotide second messengers are employed by many bacterial species to regulate various cellular processes. Here, the authors demonstrate that 2',3'-cyclic guanosine monophosphate (2',3'-cGMP) controls the important biological functions and virulence in Ralstonia solanacearum by abolishing the interaction between a transcriptional regulator and the promoters of target genes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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41. Pseudomonas chlororaphis L5 and Enterobacter asburiae L95 biocontrol Dickeya soft rot diseases by quenching virulence factor modulating quorum sensing signal.
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Liu, Fan, Hu, Ming, Tan, Xu, Xue, Yang, Li, Chuhao, Wang, Si, Lv, Mingfa, Chen, Xiaoyuan, Zhou, Xiaofan, Zhang, Lian‐hui, and Zhou, Jianuan
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QUORUM sensing ,ENTEROBACTER ,PSEUDOMONAS ,PLANT cell walls ,SIGNAL separation ,BIOLOGICAL pest control agents ,HIGH throughput screening (Drug development) ,PYRICULARIA oryzae - Abstract
Virulence factor modulating (VFM) is a quorum sensing (QS) signal shared by and specific to Dickeya bacteria, regulating the production of plant cell wall degrading enzymes (PCWDEs) and virulence of Dickeya. High polarity and trace of VFM signal increase the difficulty of signal separation and structure identification, and thus limit the development of quorum quenching strategy to biocontrol bacterial soft rot diseases caused by Dickeya. In order to high‐throughput screen VFM quenching bacteria, a vfmE‐gfp biosensor VR2 (VFM Reporter) sensitive to VFM signal was first constructed. Subsequently, two bacterial strains with high quenching efficiency were screened out by fluorescence intensity measurement and identified as Pseudomonas chlororaphis L5 and Enterobacter asburiae L95 using multilocus sequence analysis (MLSA). L5 and L95 supernatants reduced the expression of vfm genes, and both strains also decreased the production of PCWDEs of D. zeae MS2 and significantly reduced the virulence of D. oryzae EC1 on rice seedlings, D. zeae MS2 on banana seedlings, D. dadantii 3937 on potato and D. fangzhongdai CL3 on taro. Findings in this study provide a method to high‐throughput screen VFM quenching bacteria and characterize novel functions of P. chlororaphis and E. asburiae in biocontrolling plant diseases through quenching VFM QS signal. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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42. Have You Heard of Bonnie Bassler? A Historical Perspective on a Remarkable Career.
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Fuqua, Clay
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TWENTIETH century ,FLOOD warning systems ,MICROBIOLOGY ,CRISIS communication - Abstract
The area of chemical communication in bacteria has grown explosively since the end of the 20th century. Among a number of key individuals and seminal findings that broke open this area of microbiology, the contributions of Bonnie Bassler and her colleagues are immense and multi‐layered. In this short and informal review, I provide perspective on my own entry into this research field, my introduction to Dr. Bassler and her early findings, followed by the founding of the Bassler lab and the flood of brilliant experimentation and public outreach that has done so much to propel the field of bacterial chemical communication. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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43. Gram-negative bacteria resist antimicrobial agents by a DzrR-mediated envelope stress response.
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Liang, Zhibin, Lin, Qiqi, Wang, Qingwei, Huang, Luhao, Liu, Huidi, Shi, Zurong, Cui, Zining, Zhou, Xiaofan, Gao, Yong-Gui, Zhou, Jianuan, Zhang, Lian-Hui, and Deng, Yizhen
- Subjects
GRAM-negative bacteria ,ANTI-infective agents ,PHYTOPATHOGENIC microorganisms ,DRUG resistance in bacteria ,DRUG resistance in microorganisms ,RICE blast disease - Abstract
Background: Envelope stress responses (ESRs) are critical for adaptive resistance of Gram-negative bacteria to envelope-targeting antimicrobial agents. However, ESRs are poorly defined in a large number of well-known plant and human pathogens. Dickeya oryzae can withstand a high level of self-produced envelope-targeting antimicrobial agents zeamines through a zeamine-stimulated RND efflux pump DesABC. Here, we unraveled the mechanism of D. oryzae response to zeamines and determined the distribution and function of this novel ESR in a variety of important plant and human pathogens. Results: In this study, we documented that a two-component system regulator DzrR of D. oryzae EC1 mediates ESR in the presence of envelope-targeting antimicrobial agents. DzrR was found modulating bacterial response and resistance to zeamines through inducing the expression of RND efflux pump DesABC, which is likely independent on DzrR phosphorylation. In addition, DzrR could also mediate bacterial responses to structurally divergent envelope-targeting antimicrobial agents, including chlorhexidine and chlorpromazine. Significantly, the DzrR-mediated response was independent on the five canonical ESRs. We further presented evidence that the DzrR-mediated response is conserved in the bacterial species of Dickeya, Ralstonia, and Burkholderia, showing that a distantly located DzrR homolog is the previously undetermined regulator of RND-8 efflux pump for chlorhexidine resistance in B. cenocepacia. Conclusions: Taken together, the findings from this study depict a new widely distributed Gram-negative ESR mechanism and present a valid target and useful clues to combat antimicrobial resistance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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44. Perirenal fat thickness and liver fat fraction are independent predictors of MetS in adults with overweight and obesity suspected with NAFLD: a retrospective study.
- Author
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Wang, Li, Pan, Yuning, Ye, Xianwang, Zhu, Yongmeng, Lian, Yandong, Zhang, Hui, Xu, Miao, Liu, Mengxiao, and Ruan, Xinzhong
- Subjects
NON-alcoholic fatty liver disease ,ARTIFICIAL pancreases ,CHILDHOOD obesity ,LOGISTIC regression analysis ,ASPARTATE aminotransferase ,ADIPOSE tissues ,ALANINE aminotransferase ,FAT - Abstract
Background: Nonalcoholic fatty liver disease (NAFLD) has a multidirectional relationship with metabolic syndrome (MetS) and used to be considered a hepatic manifestation of MetS. Perirenal fat, as a part of visceral adipose tissue (VAT), was reported to be correlated with MetS components, but data for intraorgan fat are lacking. This study was undertaken to assess the value of peripheral and intraorgan fat to predict MetS in adults with overweight and obesity with suspected NAFLD. Methods: We studied 134 sequential adults (mean age, 31.5 years; 47% female) with overweight and obesity with suspected NAFLD. All participants underwent abdominal magnetic resonance imaging (MRI) examination. Anthropometric and metabolic parameters and perirenal fat thickness (PRFT), subcutaneous adipose tissue thickness (SATT), liver fat fraction (LFF), pancreas fat fraction (PFF), and lumbar spine fat fraction (LSFF) were collected. MetS was defined according to the International Diabetes Federation (IDF) criteria. Statistical analyses included basic statistics, linear correlation and logistic regression analysis. Results: A total of 63 adults with MetS and 71 adults with advanced liver steatosis (grades 2 and 3) were included in our study. Patients with MetS had greater PRFT (p = 0.026) and LFF (p < 0.001), as well as greater homeostasis model assessment of insulin resistance (HOMA-IR), alanine transaminase (ALT), aspartate transaminase (AST), and decreased SATT. MetS patients had a higher proportion of advanced steatosis than those without MetS (P < 0.001). The MetS score was associated with PRFT and LFF. Logistic regression analysis showed that the PRFT and LFF were independent predictors of MetS after adjusting for age and sex. A cutoff of 9.15 mm for PRFT and 14.68% for LFF could be predictive of MetS. Conclusions: This study shows that the absolute cutoff level of 9.15 mm for PRFT and 14.68% for LFF may be clinically important markers for identifying patients who are at high risk of MetS among adults with overweight and obesity with suspected NAFLD, irrespective of sex and age. Moreover, ectopic fat levels in pancreas and lumbar spine are positively associated with PRFT. Trial registration: Not applicable. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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45. tRNA modification enzyme MiaB connects environmental cues to activation of Pseudomonas aeruginosa type III secretion system.
- Author
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Lin, Qiqi, Huang, Jiahui, Liu, Zhiqing, Chen, Qunyi, Wang, Xinbo, Yu, Guohui, Cheng, Ping, Zhang, Lian-Hui, and Xu, Zeling
- Subjects
TRANSFER RNA ,PSEUDOMONAS aeruginosa ,GENETIC regulation ,GENE expression ,CELLULAR signal transduction ,ENZYMES - Abstract
Pseudomonas aeruginosa, a major inhabitant of numerous environmental reservoirs, is a momentous opportunistic human pathogen associated with severe infections even death in the patients suffering from immune deficiencies or metabolic diseases. Type III secretion system (T3SS) employed by P. aeruginosa to inject effector proteins into host cells is one of the pivotal virulence factors pertaining to acute infections caused by this pathogen. Previous studies showed that P. aeruginosa T3SS is activated by various environmental cues such as calcium concentration and the host signal spermidine. However, how T3SS is regulated and expressed particularly under the ever-changing environmental conditions remains largely elusive. In this study, we reported that a tRNA modification enzyme PA3980, designated as MiaB, positively regulated T3SS gene expression in P. aeruginosa and was essential for the induced cytotoxicity of human lung epithelial cells. Further genetic assays revealed that MiaB promoted T3SS gene expression by repressing the LadS-Gac/Rsm signaling pathway and through the T3SS master regulator ExsA. Interestingly, ladS, gacA, rsmY and rsmZ in the LadS-Gac/Rsm signaling pathway seemed potential targets under the independent regulation of MiaB. Moreover, expression of MiaB was found to be induced by the cAMP-dependent global regulator Vfr as well as the spermidine transporter-dependent signaling pathway and thereafter functioned to mediate their regulation on the T3SS gene expression. Together, these results revealed a novel regulatory mechanism for MiaB, with which it integrates different environmental cues to modulate T3SS gene expression in this important bacterial pathogen. Author summary: T3SS in P. aeruginosa is a predominant virulence factor causing acute infections in many hosts including human beings. Expression of T3SS genes is usually controlled by an intrinsic ExsECDA partner-switching cascade together with numerous extrinsic regulators with most of them are related to or inducible by different environmental cues. Whether any intermediate players exist to connect environmental cues to the activation of P. aeruginosa T3SS is not known. Here we demonstrated that a tRNA modification enzyme MiaB was upregulated by Vfr and the spermidine transporter-dependent signaling pathway, two important T3SS regulators in response to various host-related environments, to mediate their regulation on T3SS gene expression through the LadS-Gac/Rsm signaling pathway and the T3SS master regulator ExsA. Findings in this study not only advanced our understanding on the complex T3SS gene regulation in response to different environmental cues but also provided important targets for future anti-infective exploitations. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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46. Risk Factors and Molecular Mechanism of Polymyxin B Resistance in Carbapenem-Resistant Klebsiella pneumoniae Isolates from a Tertiary Hospital in Fujian, China.
- Author
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Xu, Xiaohong, Zhu, Rongping, Lian, Siyan, Zhang, Hui, Chen, Xin, Fan, Lingfang, Chen, Peisong, and Cao, Yingping
- Subjects
POLYMYXIN B ,CARBAPENEM-resistant bacteria ,KLEBSIELLA pneumoniae ,LOGISTIC regression analysis ,MICROBIAL sensitivity tests ,KLEBSIELLA infections - Abstract
Background: The emergence of polymyxin B resistance among carbapenem-resistant Klebsiella pneumoniae (CRKP) causes clinical treatment to be more difficult. We aimed to investigate the risk factors and resistance mechanisms in the polymyxin resistant CRKP (PR-CRKP) strains. Methods: From January 2021 to January 2022, 239 CRKP strains were selected, all of which were analyzed using antimicrobial susceptibility testing and clinical data. Polymerase chain reaction (PCR) was performed for the detection of resistance genes. RT-qPCR was used to quantify transcriptional levels of polymyxin resistance genes. Risk factors for polymyxin B resistant isolates were identified by logistic regression analysis. Results: The resistance rate of polymyxin B was 5.02%. In all CRKP strains, 41.84% came from the ICU. The percentage of carbapenemase producing strains was 93.72%. The main carbapenem resistance gene was bla
KPC (90.79%). In the 12 strains of PR-CRKP screened, pmrB and pmrK were overexpressed in all samples which were linked with polymyxin B resistance. Multivariate analysis showed that coronary heart disease may be an independent risk factor predisposing patients to polymyxin B resistance. Conclusion: We determine the multifaceted mechanism and risk factors of polymyxin B resistance in CRKP. Polymyxin resistance is a complex and changing problem, and more research is required. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
47. Cyclic di‐GMP modulates sessile‐motile phenotypes and virulence in Dickeya oryzae via two PilZ domain receptors.
- Author
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Chen, Yufan, Lv, Mingfa, Liang, Zhibin, Liu, Zhiqing, Zhou, Jianuan, and Zhang, Lian‐Hui
- Subjects
PHENOTYPES ,PHYTOPATHOGENIC microorganisms ,RICE seeds ,PROTEIN receptors ,PROTEOMICS - Abstract
Dickeya oryzae is a bacterial pathogen causing the severe rice stem rot disease in China and other rice‐growing countries. We showed recently that the universal bacterial second messenger c‐di‐GMP plays an important role in modulation of bacterial motility and pathogenicity, but the mechanism of regulation remains unknown. In this study, bioinformatics analysis of the D. oryzae EC1 genome led to the identification of two proteins, YcgR and BcsA, both of which contain a conserved c‐di‐GMP receptor domain, known as the PilZ‐domain. By deleting all the genes encoding c‐di‐GMP‐degrading enzymes in D. oryzae EC1, the resultant mutant 7ΔPDE with high c‐di‐GMP levels became nonmotile, formed hyperbiofilm, and lost the ability to colonize and invade rice seeds. These phenotypes were partially reversed by deletion of ycgR in the mutant 7ΔPDE, whereas deletion of bcsA only reversed the hyperbiofilm phenotype of mutant 7ΔPDE. Significantly, double deletion of ycgR and bcsA in mutant 7ΔPDE rescued its motility, biofilm formation, and virulence to levels of wild‐type EC1. In vitro biochemical experiments and in vivo phenotypic assays further validated that YcgR and BcsA proteins are the receptors for c‐di‐GMP, which together play a critical role in regulating the c‐di‐GMP‐associated functionality. The findings from this study fill a gap in our understanding of how c‐di‐GMP modulates bacterial motility and biofilm formation, and provide useful clues for further elucidation of sophisticated virulence regulatory mechanisms in this important plant pathogen. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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48. An anthranilic acid-responsive transcriptional regulator controls the physiology and pathogenicity of Ralstonia solanacearum.
- Author
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Song, Shihao, Sun, Xiuyun, Guo, Quan, Cui, Binbin, Zhu, Yu, Li, Xia, Zhou, Jianuan, Zhang, Lian-Hui, and Deng, Yinyue
- Subjects
RALSTONIA solanacearum ,AMINOBENZOIC acids ,BACTERIAL wilt diseases ,QUORUM sensing ,NOXIOUS weeds ,BACTERIAL physiology ,PHYSIOLOGY - Abstract
Quorum sensing (QS) is widely employed by bacterial cells to control gene expression in a cell density-dependent manner. A previous study revealed that anthranilic acid from Ralstonia solanacearum plays a vital role in regulating the physiology and pathogenicity of R. solanacearum. We reported here that anthranilic acid controls the important biological functions and virulence of R. solanacearum through the receptor protein RaaR, which contains helix-turn-helix (HTH) and LysR substrate binding (LysR_substrate) domains. RaaR regulates the same processes as anthranilic acid, and both are present in various bacterial species. In addition, anthranilic acid-deficient mutant phenotypes were rescued by in trans expression of RaaR. Intriguingly, we found that anthranilic acid binds to the LysR_substrate domain of RaaR with high affinity, induces allosteric conformational changes, and then enhances the binding of RaaR to the promoter DNA regions of target genes. These findings indicate that the components of the anthranilic acid signaling system are distinguished from those of the typical QS systems. Together, our work presents a unique and widely conserved signaling system that might be an important new type of cell-to-cell communication system in bacteria. Author summary: Bacterial wilt caused by Ralstonia solanacearum is one of the most widespread, harmful and destructive plant diseases in the world. Our previous study showed that the pathogenic bacterium R. solanacearum uses anthranilic acid to regulate the important biological functions, virulence and the production of quorum sensing signals. Here, we show that RaaR, a transcriptional regulator from R. solanacearum, was first identified to regulate the same phenotypes as anthranilic acid. Anthranilic acid binds to the LysR_substrate domain of RaaR and enhances the regulatory activity of RaaR to control the target gene expression, including the QS signal synthase encoding genes, phcB and solI. Both the anthranilic acid synthase TrpEG and the response regulator RaaR are present in diverse bacteria, suggesting that the anthranilic acid-type signaling system is widespread. Together, our work describes a system where a pathogen uses a single protein to control the bacterial physiology and pathogenesis by responding to anthranilic acid. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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49. Hfq Is a Critical Modulator of Pathogenicity of Dickeya oryzae in Rice Seeds and Potato Tubers.
- Author
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Shi, Zurong, Wang, Qingwei, Wang, Shunchang, Wang, Chengrun, Zhang, Lian-Hui, and Liang, Zhibin
- Subjects
RICE seeds ,POTATO seeds ,TUBERS ,NICOTIANA benthamiana ,POTATOES ,MOLECULAR chaperones ,BACTERIAL proteins ,GENE clusters - Abstract
The frequent outbreaks of soft-rot diseases caused by Dickeya oryzae have emerged as severe problems in plant production in recent years and urgently require the elucidation of the virulence mechanisms of D. oryzae. Here, we report that Hfq, a conserved RNA chaperone protein in bacteria, is involved in modulating a series of virulence-related traits and bacterial virulence in D. oryzae EC1. The findings show that the null mutation of the hfq
EC1 gene totally abolished the production of zeamine phytotoxins and protease, significantly attenuated the production of two other types of cell wall degrading enzymes, i.e., pectate lyase and cellulase, as well as attenuating swarming motility, biofilm formation, the development of hypersensitive response to Nicotiana benthamiana, and bacterial infections in rice seeds and potato tubers. QRT-PCR analysis and promoter reporter assay further indicated that HfqEC1 regulates zeamine production via modulating the expression of the key zeamine biosynthesis (zms) cluster genes. Taken together, these findings highlight that the Hfq of D. oryzae is one of the key regulators in modulating the production of virulence determinants and bacterial virulence in rice seeds and potato tubers. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
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50. Microevolution of the mexT and lasR Reinforces the Bias of Quorum Sensing System in Laboratory Strains of Pseudomonas aeruginosa PAO1.
- Author
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Liu, Yang, Ahator, Stephen Dela, Wang, Huishan, Feng, Qishun, Xu, Yinuo, Li, Chuhao, Zhou, Xiaofan, and Zhang, Lian-Hui
- Subjects
QUORUM sensing ,MICROEVOLUTION ,PSEUDOMONAS aeruginosa ,PHENOTYPIC plasticity ,GENETIC variation - Abstract
The Pseudomonas aeruginosa strain PAO1 has routinely been used as a laboratory model for quorum sensing (QS). However, the microevolution of P. aeruginosa laboratory strains resulting in genetic and phenotypic variations have caused inconsistencies in QS research. To investigate the underlying causes of these variations, we analyzed 5 Pseudomonas aeruginosa PAO1 sublines from our laboratory using a combination of phenotypic characterization, high throughput genome sequencing, and bioinformatic analysis. The major phenotypic variations among the sublines spanned across the levels of QS signals and virulence factors such as pyocyanin and elastase. Furthermore, the sublines exhibited distinct variations in motility and biofilm formation. Most of the phenotypic variations were mapped to mutations in the lasR and mexT , which are key components of the QS circuit. By introducing these mutations in the subline PAO1-E, which is devoid of such mutations, we confirmed their influence on QS, virulence, motility, and biofilm formation. The findings further highlight a possible divergent regulatory mechanism between the LasR and MexT in the P. aeruginosa. The results of our study reveal the effects of microevolution on the reproducibility of most research data from QS studies and further highlight mexT as a key component of the QS circuit of P. aeruginosa. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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