8 results on '"Li, Guan"'
Search Results
2. Mutations in enterobacterial common antigen biosynthesis restore outer membrane barrier function inEscherichia coli tol‐palmutants
- Author
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Swaine L. Chen, Wee Boon Tan, Shu-Sin Chng, Xue Li Guan, Rahul Shrivastava, Xiang'Er Jiang, and Deborah Chwee San Seow
- Subjects
Cell Membrane Permeability ,Mutant ,Biology ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,Biosynthesis ,Cell Wall ,Escherichia coli ,Homeostasis ,Molecular Biology ,Barrier function ,030304 developmental biology ,Diacylglycerol kinase ,Antigens, Bacterial ,0303 health sciences ,030306 microbiology ,Escherichia coli Proteins ,Phenotype ,Cell biology ,Bacterial Outer Membrane ,chemistry ,Mutation ,Peptidoglycan ,Periplasmic Proteins ,Cell envelope ,Bacterial outer membrane ,Biogenesis ,Bacterial Outer Membrane Proteins - Abstract
SummaryThe outer membrane (OM) is an essential component of the Gram-negative bacterial envelope that protects cells against external threats. To maintain a functional OM, cells require distinct mechanisms to ensure balance of proteins and lipids in the membrane. Mutations in OM biogenesis and/or homeostasis pathways often result in permeability defects, but how molecular changes in the OM affect barrier function is unclear. Here, we seek potential mechanism(s) that can alleviate permeability defects inEscherichia colicells lacking the Tol-Pal complex, which accumulate excess PLs in the OM. We identify mutations in enterobacterial common antigen (ECA) biosynthesis that re-establish OM barrier function against large hydrophilic molecules, yet did not restore lipid homeostasis. Furthermore, we demonstrate that build-up of biosynthetic intermediates, but not loss of ECA itself, contributes to the rescue. This suppression of OM phenotypes is unrelated to known effects that accumulation of ECA intermediates have on the cell wall. Finally, we reveal that an unusual diacylglycerol pyrophosphoryl-linked lipid species also accumulates in ECA mutants, and might play a role in the rescue phenotype. Our work provides insights into how OM barrier function can be restored independent of lipid homeostasis, and highlights previously unappreciated effects of ECA-related species in OM biology.
- Published
- 2020
3. Upregulation of Superenhancer‐Driven LncRNA FASRL by USF1 Promotes De Novo Fatty Acid Biosynthesis to Exacerbate Hepatocellular Carcinoma.
- Author
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Peng, Jiang‐Yun, Cai, Dian‐Kui, Zeng, Ren‐Li, Zhang, Chao‐Yang, Li, Guan‐Cheng, Chen, Si‐Fan, Yuan, Xiao‐Qing, and Peng, Li
- Subjects
ACETYLCOENZYME A ,FATTY acids ,HEPATOCELLULAR carcinoma ,LINCRNA ,ACETYL-CoA carboxylase ,BIOSYNTHESIS - Abstract
Superenhancers drive abnormal gene expression in tumors and promote malignancy. However, the relationship between superenhancer‐associated long noncoding RNA (lncRNA) and abnormal metabolism is unknown. This study identifies a novel lncRNA, fatty acid synthesis‐related lncRNA (FASRL), whose expression is driven by upstream stimulatory factor 1 (USF1) through its superenhancer. FASRL promotes hepatocellular carcinoma (HCC) cell proliferation in vitro and in vivo. Furthermore, FASRL binds to acetyl‐CoA carboxylase 1 (ACACA), a fatty acid synthesis rate‐limiting enzyme, increasing fatty acid synthesis via the fatty acid metabolism pathway. Moreover, the expression of FASRL, USF1, and ACACA is increased, and their high expression indicates a worse prognosis in HCC patients. In summary, USF1 drives FASRL transcription via a superenhancer. FASRL binding to ACACA increases fatty acid synthesis and lipid accumulation to mechanistically exacerbate HCC. FASRL may serve as a novel prognostic marker and treatment target in HCC. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. JASSY, a chloroplast outer membrane protein required for jasmonate biosynthesis
- Author
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Martin Lehmann, Niels Denkert, Serena Schwenkert, Li Guan, Ahmed Eisa, Michael Meinecke, Jürgen Soll, Arne Weiberg, and Inga Sjuts
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0106 biological sciences ,Chloroplasts ,Acclimatization ,Arabidopsis ,Cyclopentanes ,01 natural sciences ,Chloroplast Proteins ,03 medical and health sciences ,chemistry.chemical_compound ,Biosynthesis ,Gene Expression Regulation, Plant ,Cold acclimation ,Plant Immunity ,Oxylipins ,Jasmonate ,030304 developmental biology ,0303 health sciences ,Multidisciplinary ,biology ,Chemistry ,Membrane Proteins ,food and beverages ,Chloroplast outer membrane ,biology.organism_classification ,Cell biology ,Chloroplast ,Cytosol ,PNAS Plus ,Fatty Acids, Unsaturated ,Biogenesis ,010606 plant biology & botany - Abstract
Jasmonates are vital plant hormones that not only act in the stress response to biotic and abiotic influences, such as wounding, pathogen attack, and cold acclimation, but also drive developmental processes in cooperation with other plant hormones. The biogenesis of jasmonates starts in the chloroplast, where several enzymatic steps produce the jasmonate precursor 12-oxophytodienoic acid (OPDA) from alpha-linolenic acid. OPDA in turn is exported into the cytosol for further conversion into active jasmonates, which subsequently induces the expression of multiple genes in the nucleus. Despite its obvious importance, the export of OPDA across the chloroplast membranes has remained elusive. In this study, we characterized a protein residing in the chloroplast outer membrane, JASSY, which has proven indispensable for the export of OPDA from the chloroplast. We provide evidence that JASSY has channel-like properties and propose that it thereby facilitates OPDA transport. Consequently, a lack of JASSY in Arabidopsis leads to a deficiency in accumulation of jasmonic acids, which results in impaired expression of jasmonate target genes on exposure to various stresses. This results in plants that are more susceptible to pathogen attack and also exhibit defects in cold acclimation.
- Published
- 2019
5. Characterization of Substrate Preference for Slc1p and Cst26p in Saccharomyces cerevisiae Using Lipidomic Approaches and an LPAAT Activity Assay
- Author
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Joyce Sze Yuin Goh, Markus R. Wenk, Guanghou Shui, Yangkui Xue, Xue Li Guan, Pradeep Gopalakrishnan, and Hongyuan Yang
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Saccharomyces cerevisiae Proteins ,Science ,Saccharomyces cerevisiae ,Biology ,Mass Spectrometry ,Substrate Specificity ,Acylation ,chemistry.chemical_compound ,Biosynthesis ,Lysophosphatidic acid ,Databases, Protein ,Enzyme Assays ,chemistry.chemical_classification ,Multidisciplinary ,Fatty Acids ,Biochemistry/Chemical Biology of the Cell ,Computational Biology ,Dyneins ,Fatty acid ,Phosphatidic acid ,Lipid Metabolism ,biology.organism_classification ,chemistry ,Biochemistry ,Acyltransferases ,Acyltransferase ,Mutation ,Medicine ,Microbiology/Microbial Physiology and Metabolism ,lipids (amino acids, peptides, and proteins) ,Research Article ,Biotechnology - Abstract
BackgroundPhosphatidic acid (PA) is a key regulated intermediate and precursor for de novo biosynthesis of all glycerophospholipids. PA can be synthesized through the acylation of lysophosphatidic acid (LPA) by 1-acyl-3-phosphate acyltransferase (also called lysophosphatidic acid acyltransferase, LPAAT). Recent findings have substantiated the essential roles of acyltransferases in various biological functions.Methodologies/principal findingsWe used a flow-injection-based lipidomic approach with approximately 200 multiple reaction monitoring (MRM) transitions to pre-screen fatty acyl composition of phospholipids in the yeast Saccharomyces cerevisiae mutants. Dramatic changes were observed in fatty acyl composition in some yeast mutants including Slc1p, a well-characterized LPAAT, and Cst26p, a recently characterized phosphatidylinositol stearoyl incorporating 1 protein and putative LPAAT in S. cerevisiae. A comprehensive high-performance liquid chromatography-based multi-stage MRM approach (more than 500 MRM transitions) was developed and further applied to quantify individual phospholipids in both strains to confirm these changes. Our data suggest potential fatty acyl substrates as well as fatty acyls that compensate for defects in both Cst26p and Slc1p mutants. These results were consistent with those from a non-radioactive LPAAT enzymatic assay using C17-LPA and acyl-CoA donors as substrates.ConclusionsWe found that Slc1p utilized fatty acid (FA) 18:1 and FA 14:0 as substrates to synthesize corresponding PAs; moreover, it was probably the only acyltransferase responsible for acylation of saturated short-chain fatty acyls (12:0 and 10:0) in S. cerevisiae. We also identified FA 18:0, FA 16:0, FA 14:0 and exogenous FA 17:0 as preferred substrates for Cst26p because transformation with a GFP-tagged CST26 restored the phospholipid profile of a CST26 mutant. Our current findings expand the enzymes and existing scope of acyl-CoA donors for glycerophospholipid biosynthesis.
- Published
- 2010
6. Characterization of Substrate Preference for Slc1p and Cst26p in Saccharomyces cerevisiae Using Lipidomic Approaches and an LPAAT Activity Assay.
- Author
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Shui, Guanghou, Xue Li Guan, Gopalakrishnan, Pradeep, Yangkui Xue, Joyce Sze Yuin Goh, Hongyuan Yang, and Wenk, Markus R.
- Subjects
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PHOSPHATIDIC acids , *PROTEIN precursors , *SACCHAROMYCES cerevisiae , *LYSOPHOSPHOLIPIDS , *ACYLTRANSFERASES , *YEAST , *PHOSPHOINOSITIDES , *BIOSYNTHESIS , *ACYLATION , *LIQUID chromatography - Abstract
Background: Phosphatidic acid (PA) is a key regulated intermediate and precursor for de novo biosynthesis of all glycerophospholipids. PA can be synthesized through the acylation of lysophosphatidic acid (LPA) by 1-acyl-3-phosphate acyltransferase (also called lysophosphatidic acid acyltransferase, LPAAT). Recent findings have substantiated the essential roles of acyltransferases in various biological functions. Methodologies/Principal Findings: We used a flow-injection-based lipidomic approach with ∼200 multiple reaction monitoring (MRM) transitions to pre-screen fatty acyl composition of phospholipids in the yeast Saccharomyces cerevisiae mutants. Dramatic changes were observed in fatty acyl composition in some yeast mutants including Slc1p, a wellcharacterized LPAAT, and Cst26p, a recently characterized phosphatidylinositol stearoyl incorporating 1 protein and putative LPAAT in S. cerevisiae. A comprehensive high-performance liquid chromatography-based multi-stage MRM approach (more than 500 MRM transitions) was developed and further applied to quantify individual phospholipids in both strains to confirm these changes. Our data suggest potential fatty acyl substrates as well as fatty acyls that compensate for defects in both Cst26p and Slc1p mutants. These results were consistent with those from a non-radioactive LPAAT enzymatic assay using C17-LPA and acyl-CoA donors as substrates. Conclusions: We found that Slc1p utilized fatty acid (FA) 18:1 and FA 14:0 as substrates to synthesize corresponding PAs; moreover, it was probably the only acyltransferase responsible for acylation of saturated short-chain fatty acyls (12:0 and 10:0) in S. cerevisiae. We also identified FA 18:0, FA 16:0, FA 14:0 and exogenous FA 17:0 as preferred substrates for Cst26p because transformation with a GFP-tagged CST26 restored the phospholipid profile of a CST26 mutant. Our current findings expand the enzymes and existing scope of acyl-CoA donors for glycerophospholipid biosynthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
7. OsABF1 Represses Gibberellin Biosynthesis to Regulate Plant Height and Seed Germination in Rice (Oryza sativa L.).
- Author
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Tang, Liqun, Xu, Huayu, Wang, Yifeng, Wang, Huimei, Li, Zhiyong, Liu, Xixi, Shu, Yazhou, Li, Guan, Liu, Wanning, Ying, Jiezheng, Tong, Xiaohong, Yao, Jialing, Xiao, Wenfei, Tang, Shaoqing, Ni, Shen, and Zhang, Jian
- Subjects
RICE ,RICE seeds ,GERMINATION ,BIOSYNTHESIS ,HOMEOSTASIS ,GREEN Revolution - Abstract
Gibberellins (GAs) are diterpenoid phytohormones regulating various aspects of plant growth and development, such as internode elongation and seed germination. Although the GA biosynthesis pathways have been identified, the transcriptional regulatory network of GA homeostasis still remains elusive. Here, we report the functional characterization of a GA-inducible OsABF1 in GA biosynthesis underpinning plant height and seed germination. Overexpression of OsABF1 produced a typical GA-deficient phenotype with semi-dwarf and retarded seed germination. Meanwhile, the phenotypes could be rescued by exogenous GA
3 , suggesting that OsABF1 is a key regulator of GA homeostasis. OsABF1 could directly suppress the transcription of green revolution gene SD1, thus reducing the endogenous GA level in rice. Moreover, OsABF1 interacts with and transcriptionally antagonizes to the polycomb repression complex component OsEMF2b, whose mutant showed as similar but more severe phenotype to OsABF1 overexpression lines. It is suggested that OsABF1 recruits RRC2-mediated H3K27me3 deposition on the SD1 promoter, thus epigenetically silencing SD1 to maintain the GA homeostasis for growth and seed germination. These findings shed new insight into the functions of OsABF1 and regulatory mechanism underlying GA homeostasis in rice. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
8. The translocator maintenance protein Tam41 is required for mitochondrial cardiolipin biosynthesis.
- Author
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Kutik, Stephan, Rissler, Michael, Xue Li Guan, Guiard, Bernard, Shui, Guanghou, Gebert, Natalia, Heacock, Philip N., Rehling, Peter, Dowhan, William, Wenk, Markus R., Pfanner, Nikolaus, and Wiedemann, Nils
- Subjects
- *
PROTEINS , *CHROMOSOMAL translocation , *BIOSYNTHESIS , *CARDIOLIPIN , *MITOCHONDRIAL membranes , *CARRIER proteins - Abstract
The mitochondrial inner membrane contains different translocator systems for the import of presequence-carrying proteins and carrier proteins. The translocator assembly and maintenance protein 41 (Tam41/ mitochondrial matrix protein 37) was identified as a new member of the mitochondrial protein translocator systems by its role in maintaining the integrity and activity of the presequence translocase of the inner membrane (TIM23 complex). Here we demonstrate that the assembly of proteins imported by the carrier translocase, TIM22 complex, is even more strongly affected by the lack of Tam41. Moreover, respiratory chain supercomplexes and the inner membrane potential are impaired by lack of Tam41. The phenotype of Tam41-deficient mitochondria thus resembles that of mitochondria lacking cardiolipin. Indeed, we found that Tam41 is required for the biosynthesis of the dimeric phospholipid cardiolipin. The pleiotropic effects of the translocator maintenance protein on preprotein import and respiratory chain can be attributed to its role in biosynthesis of mitochondrial cardiolipin. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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