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5. Comparative genomic analysis of the thermophilic biomass-degrading fungi Myceliophthora thermophila and Thielavia terrestris

Author

Berka, Randy M., Grigoriev, Igor V., Otillar, Robert, Salamov, Asaf, Grimwood, Jane, Reid, Ian, Ishmael, Nadeeza, John, Tricia, Darmond, Corinne, Moisan, Marie-Claude, Henrissat, Bernard, Coutinho, Pedro M., Lombard, Vincent, Natvig, Donald O., Lindquist, Erika, Schmutz, Jeremy, Lucas, Susan, Harris, Paul, Powlowski, Justin, Bellemare, Annie, Taylor, David, Butler, Gregory, Vries, Ronald P. de, Allijn, Iris E., Brink, Joost van den, Ushinsky, Sophia, Storms, Reginald, Powell, Amy J., Paulsen, Ian T., Elbourne, Liam D. H., Baker, Scott. E., Magnuson, Jon, LaBoissiere, Sylvie, Clutterbuck, A. John, Martinez, Diego, Wogulis, Mark, Leon, Alfredo Lopez de, Rey, Michael W., and Tsang, Adrian

Abstract

Thermostable enzymes and thermophilic cell factories may afford economic advantages in the production of many chemicals and biomass-based fuels. Here we describe and compare the genomes of two thermophilic fungi, Myceliophthora thermophila and Thielavia terrestris. To our knowledge, these genomes are the first described for thermophilic eukaryotes and the first complete telomere-to-telomere genomes for filamentous fungi. Genome analyses and experimental data suggest that both thermophiles are capable of hydrolyzing all major polysaccharides found in biomass. Examination of transcriptome data and secreted proteins suggests that the two fungi use shared approaches in the hydrolysis of cellulose and xylan but distinct mechanisms in pectin degradation. Characterization of the biomass-hydrolyzing activity of recombinant enzymes suggests that these organisms are highly efficient in biomass decomposition at both moderate and high temperatures. Furthermore, we present evidence suggesting that aside from representing a potential reservoir of thermostable enzymes, thermophilic fungi are amenable to manipulation using classical and molecular genetics.

Published
2011

12. Additional file 11 of Farnesyl pyrophosphate compartmentalization in the green microalga Chlamydomonas reinhardtii during heterologous (E)-α-bisabolene production

Author

Wichmann, Julian, Eggert, Annibel, Elbourne, Liam D. H., Paulsen, Ian T., Lauersen, Kyle J., and Kruse, Olaf

Abstract

Additional file 11: Figure S1. Attempts to increase flux towards cytosolic FPP by CrFPPS accumulation. Different orientations with the mCerulean3 reporter and co-expression of AgBS and corresponding bisabolene yields (fg cell−1) are depicted (constructs indicated on the left). Error bars represent 95% confidence intervals. Figure S2. Detection of full-length protein products of 3 independent cell lines transformed with various constructs. Each cell line is denoted by individual numbers, constructs are specified at the top, and corresponding bisabolene yields are depicted in Fig. 2. Total cellular proteins were run on a 10% SDS PAGE gel and subjected to Western blotting with α-GFP antibody. M marker (PageRuler prestained protein ladder, ThermoFisher Scientific). WT parental strain UVM4. P positive control expressing AgBS-mVenus, AgBS-mCerulean3, and AgBS-mRuby2 to the cytosol. Positive control and ERG20 protein products show previously observed pattern of protein breakage in the reporter [7]. Predicted protein sizes are: ~ 124.0 kDa for AgBS-mVenus, ~ 70.2 kDa for ERG20-mCerulean3, and ~ 67.7 kDa for mCerulean3-ERG20 which lacks a StrepII tag on its C terminus. Figure S3. Detection of full-length protein products of 3 independent cell lines transformed with various constructs. Each cell line is denoted by individual numbers, constructs are specified at the top, and corresponding bisabolene yields are depicted in Fig. 3. Total cellular proteins were run on a 10% SDS PAGE gel and subjected to Western blotting with α-GFP antibody. M marker (PageRuler prestained protein plus ladder, ThermoFisher Scientific). WT parental strain UVM4. Y mVenus expressed to the cytosol. Predicted protein sizes are: ~ 124.0 kDa for AgBS-mVenus, ~ 161.9 kDa for AgBS-mVenus-ERG20. Ponceau S stain is shown as loading control on the nitrocellulose membrane. Signal for construct vi, strain #3 was below detection limit, but bisabolene could be detected in GC–MS measurements, indicating full-length expression. Figure S4. Detection of full-length protein products of 3 independent cell lines transformed with various constructs. Each cell line is denoted by individual numbers, constructs are specified at the top, and corresponding bisabolene yields are depicted in Fig. 4. Total cellular proteins were run on a 10% SDS PAGE gel and subjected to Western blotting with α-GFP and α-StrepII antibodies. M marker (PageRuler prestained protein ladder, ThermoFisher Scientific). WT parental strain UVM4. P positive control expressing AgBS-mVenus, AgBS-mCerulean3, and AgBS-mRuby2 to the cytosol. Positive control and ERG20 protein products show previously observed pattern of protein breakage in the reporter [7]. Predicted protein sizes are: ~ 124.0 kDa for AgBS-mVenus, ~ 123.1 kDa for AgBS-mCerulean3, ~ 120.9 kDa for AgBS-mRuby2, ~ 123.7 kDa for AgBS-aadA, ~ 67.7 kDa for mCerulean3-ERG20 which lacks a StrepII tag on its C terminus, ~ 161.9 kDa for AgBS-mVenus-ERG20, and ~ 162.2 kDa for AgBS-mCerulean3-ERG20. Figure S5. Detection of full-length protein products of 3 independent cell lines transformed with various constructs. Each cell line is denoted by individual numbers, constructs are specified at the top, and corresponding bisabolene yields are depicted in Fig. 3 and Additional file 11 Fig. S1. Total cellular proteins were run on a 10% SDS PAGE gel and subjected to Western blotting with α-GFP antibodies. M marker (PageRuler prestained protein ladder, ThermoFisher Scientific). WT parental strain UVM4. CrFPPS protein products show previously observed pattern of protein breakage in the reporter [7]. Predicted protein sizes are: ~ 160.9 kDa for AgBS-mVenus-CrFPPS, ~ 124.0 kDa for AgBS-mVenus, ~ 68.5 kDa for CrFPPS-mCerulean3, and ~ 67.0 kDa for mCerulean3-CrFPPS which lacks a StrepII tag on its C terminus. Figure S6. Calibration line and correspondent equation for bisabolene quantification. GC/MS peak areas were normalized to the internal standard peak area, and plotted against the bisabolene concentration in dodecane.

Published
2022
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13. Farnesyl pyrophosphate compartmentalization in the green microalga Chlamydomonasreinhardtii during heterologous (E)-alpha-bisabolene production

Author

Wichmann, Julian, Eggert, Annibel, Elbourne, Liam D H, Paulsen, Ian T, Lauersen, Kyle J., and Kruse, Olaf

Subjects
Neoprene, Polyisoprenyl Phosphates, Terpenes, Microalgae, Plants, Sesquiterpenes, Carbon, Chlamydomonas reinhardtii
Abstract

BACKGROUND: Eukaryotic algae have recently emerged as hosts for metabolic engineering efforts to generate heterologous isoprenoids. Isoprenoid metabolic architectures, flux, subcellular localization, and transport dynamics have not yet been fully elucidated in algal hosts.; RESULTS: In this study, we investigated the accessibility of different isoprenoid precursor pools for C15 sesquiterpenoid generation in the cytoplasm and chloroplast of Chlamydomonas reinhardtii using the Abies grandis bisabolene synthase (AgBS) as a reporter. The abundance of the C15 sesquiterpene precursor farnesyl pyrophosphate (FPP) was not increased in the cytosol by co-expression and fusion of AgBS with different FPP synthases (FPPSs), indicating limited C5 precursor availability in the cytoplasm. However, FPP was shown to be available in the plastid stroma, where bisabolene titers could be improved several-fold by FPPSs. Sesquiterpene production was greatest when AgBS-FPPS fusions were directed to the plastid and could further be improved by increasing the gene dosage. During scale-up cultivation with different carbon sources and light regimes, specific sesquiterpene productivities from the plastid were highest with CO2 as the only carbon source and light:dark illumination cycles. Potential prenyl unit transporters are proposed based on bioinformatic analyses, which may be in part responsible for our observations.; CONCLUSIONS: Our findings indicate that the algal chloroplast can be harnessed in addition to the cytosol to exploit the full potential of algae as green cell factories for non-native sesquiterpenoid generation. Identification of a prenyl transporter may be leveraged for further extending this capacity. © 2022. The Author(s).

Published
2022

14. Additional file 1 of Exploring the transportome of the biosurfactant producing yeast Starmerella bombicola

Author

Claus, Silke, Jezierska, Sylwia, Elbourne, Liam D. H., and Van Bogaert, Inge

Abstract

Additional file 1: Table S1. Summary table of S. bombicola���s predicted transporters. Table S2. Keys for TransAAP substrate prediction, grouped. Table S3. S. bombicola strains used in this research. Table S4. Primers used in this research. Table S5. Maximum specific growth rate (��) of selected S. bombicola ABC transporter knockouts cultivated on SD medium. Table S6. List of compounds used for disc diffusion assay, their concentration in DMSO and supplier. Figure S1. Disc diffusion assay with polyoxyethylene-9-lauryl ether of selected S. bombicola ABC transporter deletion mutants compared to wild type. Figure S2. Disc diffusion assay of S. bombicola ��SbCdr4 and S. bombicola ��SbYor1.2 compared to wild type. The concentration of the applied medium chain alkanes and fatty alcohols is given in Table S6. Figure S3. Comparison of growth among different SL transporter deletion strains on shake flask scale by OD600 and pH measurements every 24 h (a) without the addition of rapeseed oil and (b) with the addition of 37.5 g/L rapeseed oil.

Published
2022
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16. Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes in Rhizosphere Pseudomonas

Author

Mavrodi, Olga V., primary, McWilliams, Janiece R., additional, Peter, Jacob O., additional, Berim, Anna, additional, Hassan, Karl A., additional, Elbourne, Liam D. H., additional, LeTourneau, Melissa K., additional, Gang, David R., additional, Paulsen, Ian T., additional, Weller, David M., additional, Thomashow, Linda S., additional, Flynt, Alex S., additional, and Mavrodi, Dmitri V., additional

Published
2021
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19. The effect of root exudates on the transcriptome of rhizospherePseudomonasspp

Author

Mavrodi, Olga V., primary, McWilliams, Janiece R., additional, Peter, Jacob O., additional, Berim, Anna, additional, Hassan, Karl A., additional, Elbourne, Liam D. H., additional, LeTourneau, Melissa K., additional, Gang, David R., additional, Paulsen, Ian T., additional, Weller, David M., additional, Thomashow, Linda S., additional, Flynt, Alex S., additional, and Mavrodi, Dmitri V., additional

Published
2021
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21. Dual Transcriptomics of Host-Pathogen Interaction of Cystic Fibrosis Isolate Pseudomonas aeruginosa PASS1 With Zebrafish

Author

Kumar, Sheemal S., primary, Tandberg, Julia I., additional, Penesyan, Anahit, additional, Elbourne, Liam D. H., additional, Suarez-Bosche, Nadia, additional, Don, Emily, additional, Skadberg, Eline, additional, Fenaroli, Federico, additional, Cole, Nicholas, additional, Winther-Larsen, Hanne Cecilie, additional, and Paulsen, Ian T., additional

Published
2018
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22. Genome‐based evolutionary history of Pseudomonas spp

Author

Hesse, Cedar, primary, Schulz, Frederik, additional, Bull, Carolee T., additional, Shaffer, Brenda T., additional, Yan, Qing, additional, Shapiro, Nicole, additional, Hassan, Karl A., additional, Varghese, Neha, additional, Elbourne, Liam D. H., additional, Paulsen, Ian T., additional, Kyrpides, Nikos, additional, Woyke, Tanja, additional, and Loper, Joyce E., additional

Published
2018
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25. The putative drug efflux systems of the Bacillus cereus group

Author

Hassan, Karl A., primary, Fagerlund, Annette, additional, Elbourne, Liam D. H., additional, Vörös, Aniko, additional, Kroeger, Jasmin K., additional, Simm, Roger, additional, Tourasse, Nicolas J., additional, Finke, Sarah, additional, Henderson, Peter J. F., additional, Økstad, Ole Andreas, additional, Paulsen, Ian T., additional, and Kolstø, Anne-Brit, additional

Published
2017
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28. Fluorescence-Based Flow Sorting in Parallel with Transposon Insertion Site Sequencing Identifies Multidrug Efflux Systems in Acinetobacter baumannii

Author

Hassan, Karl A., primary, Cain, Amy K., additional, Huang, TaoTao, additional, Liu, Qi, additional, Elbourne, Liam D. H., additional, Boinett, Christine J., additional, Brzoska, Anthony J., additional, Li, Liping, additional, Ostrowski, Martin, additional, Nhu, Nguyen Thi Khanh, additional, Nhu, Tran Do Hoang, additional, Baker, Stephen, additional, Parkhill, Julian, additional, and Paulsen, Ian T., additional

Published
2016
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30. An ace up their sleeve: a transcriptomic approach exposes the AceI efflux protein of Acinetobacter baumannii and reveals the drug efflux potential hidden in many microbial pathogens

Author

Hassan, Karl A., primary, Elbourne, Liam D. H., additional, Li, Liping, additional, Gamage, Hasinika K. A. H., additional, Liu, Qi, additional, Jackson, Scott M., additional, Sharples, David, additional, Kolstø, Anne-Brit, additional, Henderson, Peter J. F., additional, and Paulsen, Ian T., additional

Published
2015
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36. Maintenance of essential amino acid synthesis pathways in the Blattabacterium cuenoti symbiont of a wood-feeding cockroach

Author

Tokuda, Gaku, primary, Elbourne, Liam D. H., additional, Kinjo, Yukihiro, additional, Saitoh, Seikoh, additional, Sabree, Zakee, additional, Hojo, Masaru, additional, Yamada, Akinori, additional, Hayashi, Yoshinobu, additional, Shigenobu, Shuji, additional, Bandi, Claudio, additional, Paulsen, Ian T., additional, Watanabe, Hirofumi, additional, and Lo, Nathan, additional

Published
2013
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40. Comparative Genomics of Plant-Associated Pseudomonas spp.: Insights into Diversity and Inheritance of Traits Involved in Multitrophic Interactions

Author

Loper, Joyce E., primary, Hassan, Karl A., additional, Mavrodi, Dmitri V., additional, Davis, Edward W., additional, Lim, Chee Kent, additional, Shaffer, Brenda T., additional, Elbourne, Liam D. H., additional, Stockwell, Virginia O., additional, Hartney, Sierra L., additional, Breakwell, Katy, additional, Henkels, Marcella D., additional, Tetu, Sasha G., additional, Rangel, Lorena I., additional, Kidarsa, Teresa A., additional, Wilson, Neil L., additional, van de Mortel, Judith E., additional, Song, Chunxu, additional, Blumhagen, Rachel, additional, Radune, Diana, additional, Hostetler, Jessica B., additional, Brinkac, Lauren M., additional, Durkin, A. Scott, additional, Kluepfel, Daniel A., additional, Wechter, W. Patrick, additional, Anderson, Anne J., additional, Kim, Young Cheol, additional, Pierson, Leland S., additional, Pierson, Elizabeth A., additional, Lindow, Steven E., additional, Kobayashi, Donald Y., additional, Raaijmakers, Jos M., additional, Weller, David M., additional, Thomashow, Linda S., additional, Allen, Andrew E., additional, and Paulsen, Ian T., additional

Published
2012
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41. Comparative genomic analysis of the thermophilic biomass-degrading fungi Myceliophthora thermophila and Thielavia terrestris

Author

Berka, Randy M, primary, Grigoriev, Igor V, additional, Otillar, Robert, additional, Salamov, Asaf, additional, Grimwood, Jane, additional, Reid, Ian, additional, Ishmael, Nadeeza, additional, John, Tricia, additional, Darmond, Corinne, additional, Moisan, Marie-Claude, additional, Henrissat, Bernard, additional, Coutinho, Pedro M, additional, Lombard, Vincent, additional, Natvig, Donald O, additional, Lindquist, Erika, additional, Schmutz, Jeremy, additional, Lucas, Susan, additional, Harris, Paul, additional, Powlowski, Justin, additional, Bellemare, Annie, additional, Taylor, David, additional, Butler, Gregory, additional, de Vries, Ronald P, additional, Allijn, Iris E, additional, van den Brink, Joost, additional, Ushinsky, Sophia, additional, Storms, Reginald, additional, Powell, Amy J, additional, Paulsen, Ian T, additional, Elbourne, Liam D H, additional, Baker, Scott E, additional, Magnuson, Jon, additional, LaBoissiere, Sylvie, additional, Clutterbuck, A John, additional, Martinez, Diego, additional, Wogulis, Mark, additional, de Leon, Alfredo Lopez, additional, Rey, Michael W, additional, and Tsang, Adrian, additional

Published
2011
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42. Genome Sequences of the Biotechnologically Important Bacillus megaterium Strains QM B1551 and DSM319

Author

Eppinger, Mark, primary, Bunk, Boyke, additional, Johns, Mitrick A., additional, Edirisinghe, Janaka N., additional, Kutumbaka, Kirthi K., additional, Koenig, Sara S. K., additional, Huot Creasy, Heather, additional, Rosovitz, M. J., additional, Riley, David R., additional, Daugherty, Sean, additional, Martin, Madeleine, additional, Elbourne, Liam D. H., additional, Paulsen, Ian, additional, Biedendieck, Rebekka, additional, Braun, Christopher, additional, Grayburn, Scott, additional, Dhingra, Sourabh, additional, Lukyanchuk, Vitaliy, additional, Ball, Barbara, additional, Ul-Qamar, Riaz, additional, Seibel, Jürgen, additional, Bremer, Erhard, additional, Jahn, Dieter, additional, Ravel, Jacques, additional, and Vary, Patricia S., additional

Published
2011
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44. The Rsm regulon of plant growth-promoting P seudomonas fluorescens SS101: role of small RNAs in regulation of lipopeptide biosynthesis.

Author

Song, Chunxu, Voort, Menno, Mortel, Judith, Hassan, Karl A., Elbourne, Liam D. H., Paulsen, Ian T., Loper, Joyce E., and Raaijmakers, Jos M.

Subjects
BACTERIAL metabolites, GENETIC regulation, REGULONS, PSEUDOMONAS fluorescens, NON-coding RNA, LIPOPEPTIDE antibiotics, BIOSYNTHESIS, PLANT growth, BACTERIA
Abstract

The rhizobacterium P seudomonas fluorescens SS101 inhibits growth of oomycete and fungal pathogens, and induces resistance in plants against pathogens and insects. To unravel regulatory pathways of secondary metabolite production in SS101, we conducted a genome-wide search for sRNAs and performed transcriptomic analyses to identify genes associated with the Rsm ( repressor of secondary metabolites) regulon. In silico analysis led to the identification of 16 putative sRNAs in the SS101 genome. In frame deletion of the sRNAs rsmY and rsmZ showed that the Rsm system regulates the biosynthesis of the lipopeptide massetolide A and involves the two repressor proteins RsmA and RsmE, with the LuxR-type transcriptional regulator MassAR as their most likely target. Transcriptome analyses of the rsmYZ mutant further revealed that genes associated with iron acquisition, motility and chemotaxis were significantly upregulated, whereas genes of the type VI secretion system were downregulated. Comparative transcriptomic analyses showed that most, but not all, of the genes controlled by RsmY/ RsmZ are also controlled by the GacS/ GacA two-component system. We conclude that the Rsm regulon of P. fluorescens SS101 plays a critical role in the regulation of lipopeptide biosynthesis and controls the expression of other genes involved in motility, competition and survival in the plant rhizosphere. [ABSTRACT FROM AUTHOR]

Published
2015
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48. The Complete Genome and Phenome of a Community-Acquired Acinetobacter baumannii.

Author

Farrugia, Daniel N., Elbourne, Liam D. H., Hassan, Karl A., Eijkelkamp, Bart A., Tetu, Sasha G., Brown, Melissa H., Shah, Bhumika S., Peleg, Anton Y., Mabbutt, Bridget C., and Paulsen, Ian T.

Subjects
*ACINETOBACTER baumannii, *BIOTIC communities, *PATHOGENIC bacteria, *BACTERIAL genomes, *DISEASE susceptibility, *COMPARATIVE studies, *NITROGEN compounds
Abstract

Many sequenced strains of Acinetobacter baumannii are established nosocomial pathogens capable of resistance to multiple antimicrobials. Community-acquired A. baumannii in contrast, comprise a minor proportion of all A. baumannii infections and are highly susceptible to antimicrobial treatment. However, these infections also present acute clinical manifestations associated with high reported rates of mortality. We report the complete 3.70 Mbp genome of A. baumannii D1279779, previously isolated from the bacteraemic infection of an Indigenous Australian; this strain represents the first community-acquired A. baumannii to be sequenced. Comparative analysis of currently published A. baumannii genomes identified twenty-four accessory gene clusters present in D1279779. These accessory elements were predicted to encode a range of functions including polysaccharide biosynthesis, type I DNA restriction-modification, and the metabolism of novel carbonaceous and nitrogenous compounds. Conversely, twenty genomic regions present in previously sequenced A. baumannii strains were absent in D1279779, including gene clusters involved in the catabolism of 4-hydroxybenzoate and glucarate, and the A. baumannii antibiotic resistance island, known to bestow resistance to multiple antimicrobials in nosocomial strains. Phenomic analysis utilising the Biolog Phenotype Microarray system indicated that A. baumannii D1279779 can utilise a broader range of carbon and nitrogen sources than international clone I and clone II nosocomial isolates. However, D1279779 was more sensitive to antimicrobial compounds, particularly beta-lactams, tetracyclines and sulphonamides. The combined genomic and phenomic analyses have provided insight into the features distinguishing A. baumannii isolated from community-acquired and nosocomial infections. [ABSTRACT FROM AUTHOR]

Published
2013
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49. The Complete Genome and Phenome of a Community-Acquired Acinetobacter baumannii.

Author

Farrugia, Daniel N., Elbourne, Liam D. H., Hassan, Karl A., Eijkelkamp, Bart A., Tetu, Sasha G., Brown, Melissa H., Shah, Bhumika S., Peleg, Anton Y., Mabbutt, Bridget C., and Paulsen, Ian T.

Subjects
ACINETOBACTER baumannii, BIOTIC communities, PATHOGENIC bacteria, BACTERIAL genomes, DISEASE susceptibility, COMPARATIVE studies, NITROGEN compounds
Abstract

Many sequenced strains of Acinetobacter baumannii are established nosocomial pathogens capable of resistance to multiple antimicrobials. Community-acquired A. baumannii in contrast, comprise a minor proportion of all A. baumannii infections and are highly susceptible to antimicrobial treatment. However, these infections also present acute clinical manifestations associated with high reported rates of mortality. We report the complete 3.70 Mbp genome of A. baumannii D1279779, previously isolated from the bacteraemic infection of an Indigenous Australian; this strain represents the first community-acquired A. baumannii to be sequenced. Comparative analysis of currently published A. baumannii genomes identified twenty-four accessory gene clusters present in D1279779. These accessory elements were predicted to encode a range of functions including polysaccharide biosynthesis, type I DNA restriction-modification, and the metabolism of novel carbonaceous and nitrogenous compounds. Conversely, twenty genomic regions present in previously sequenced A. baumannii strains were absent in D1279779, including gene clusters involved in the catabolism of 4-hydroxybenzoate and glucarate, and the A. baumannii antibiotic resistance island, known to bestow resistance to multiple antimicrobials in nosocomial strains. Phenomic analysis utilising the Biolog Phenotype Microarray system indicated that A. baumannii D1279779 can utilise a broader range of carbon and nitrogen sources than international clone I and clone II nosocomial isolates. However, D1279779 was more sensitive to antimicrobial compounds, particularly beta-lactams, tetracyclines and sulphonamides. The combined genomic and phenomic analyses have provided insight into the features distinguishing A. baumannii isolated from community-acquired and nosocomial infections. [ABSTRACT FROM AUTHOR]

Published
2013
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50. H-NS Plays a Role in Expression of Acinetobacter baumanniiVirulence Features

Author

Eijkelkamp, Bart A., Stroeher, Uwe H., Hassan, Karl A., Elbourne, Liam D. H., Paulsen, Ian T., and Brown, Melissa H.

Abstract

ABSTRACTAcinetobacter baumanniihas become a major problem in the clinical setting with the prevalence of infections caused by multidrug-resistant strains on the increase. Nevertheless, only a limited number of molecular mechanisms involved in the success of A. baumanniias a human pathogen have been described. In this study, we examined the virulence features of a hypermotile derivative of A. baumanniistrain ATCC 17978, which was found to display enhanced adherence to human pneumocytes and elevated levels of lethality toward Caenorhabditis elegansnematodes. Analysis of cellular lipids revealed modifications to the fatty acid composition, providing a possible explanation for the observed changes in hydrophobicity and subsequent alteration in adherence and motility. Comparison of the genome sequences of the hypermotile variant and parental strain revealed that an insertion sequence had disrupted an hns-like gene in the variant. This gene encodes a homologue of the histone-like nucleoid structuring (H-NS) protein, a known global transcriptional repressor. Transcriptome analysis identified the global effects of this mutation on gene expression, with major changes seen in the autotransporter Ata, a type VI secretion system, and a type I pilus cluster. Interestingly, isolation and analysis of a second independent hypermotile ATCC 17978 variant revealed a mutation to a residue within the DNA binding region of H-NS. Taken together, these mutants indicate that the phenotypic and transcriptomic differences seen are due to loss of regulatory control effected by H-NS.

Published
2013
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