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Staphylococcus epidermidis SrrAB regulates bacterial growth and biofilm formation differently under oxic and microaerobic conditions

Wu, Youcong
Wu, Yang
Zhu, Tao
Han, Haiyan
Liu, Huayong
Xu, Tao
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Published in Journal of Bacteriology. 2015, vol. 197, no. 3, p. 459-76
Abstract SrrAB expression in Staphylococcus epidermidis strain 1457 (SE1457) was upregulated during a shift from oxic to microaerobic conditions. An srrA deletion (ΔsrrA) mutant was constructed for studying the regulatory function of SrrAB. The deletion resulted in retarded growth and abolished biofilm formation both in vitro and in vivo and under both oxic and microaerobic conditions. Associated with the reduced biofilm formation, the ΔsrrA mutant produced much less polysaccharide intercellular adhesion (PIA) and showed decreased initial adherence capacity. Microarray analysis showed that the srrA mutation affected transcription of 230 genes under microaerobic conditions, and 51 genes under oxic conditions. Quantitative real-time PCR confirmed this observation and showed downregulation of genes involved in maintaining the electron transport chain by supporting cytochrome and quinol-oxidase assembly (e.g., qoxB and ctaA) and in anaerobic metabolism (e.g., pflBA and nrdD). In the ΔsrrA mutant, the expression of the biofilm formation-related gene icaR was upregulated under oxic conditions and downregulated under microaerobic conditions, whereas icaA was downregulated under both conditions. An electrophoretic mobility shift assay further revealed that phosphorylated SrrA bound to the promoter regions of icaR, icaA, qoxB, and pflBA, as well as its own promoter region. These findings demonstrate that in S. epidermidis SrrAB is an autoregulator and regulates biofilm formation in an ica-dependent manner. Under oxic conditions, SrrAB modulates electron transport chain activity by positively regulating qoxBACD transcription. Under microaerobic conditions, it regulates fermentation processes and DNA synthesis by modulating the expression of both the pfl operon and nrdDG.
Keywords AerobiosisAnaerobiosisBacterial AdhesionBiofilms/growth & developmentDNA, Bacterial/metabolismElectron TransportElectrophoretic Mobility Shift AssayGene DeletionGene Expression ProfilingMicroarray AnalysisOxygen/metabolismPolysaccharides, Bacterial/metabolismPromoter Regions, GeneticProtein BindingReal-Time Polymerase Chain ReactionStaphylococcus epidermidis/drug effects/genetics/growth & development/physiologyTranscription Factors/genetics/metabolism
PMID: 25404696
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Research group Analyse génomique et fonctionnelle du staphylocoque doré (604)
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WU, Youcong et al. Staphylococcus epidermidis SrrAB regulates bacterial growth and biofilm formation differently under oxic and microaerobic conditions. In: Journal of Bacteriology, 2015, vol. 197, n° 3, p. 459-76. https://archive-ouverte.unige.ch/unige:74130

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Deposited on : 2015-07-14

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