Staphylococcus epidermidis SrrAB Regulates Bacterial Growth and Biofilm Formation Differently under Oxic and Microaerobic Conditions
Staphylococcus epidermidis SrrAB Regulates Bacterial Growth and Biofilm Formation Differently under Oxic and Microaerobic Conditions
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DOI：
10.1128/jb.02231-14
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发表时间：
2014-11
影响因子：
3.2
通讯作者：
Youcong Wu;Yang Wu;T. Zhu;Haiyan Han;Huayong Liu;Tao Xu;P. François;A. Fischer;Li Bai
中科院分区：
文献类型：
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作者：
Youcong Wu;Yang Wu;T. Zhu;Haiyan Han;Huayong Liu;Tao Xu;P. François;A. Fischer;Li Bai
表皮葡萄球菌菌株1457（SE 1457）中SrrAB的表达在从好氧条件到微好氧条件的转变过程中上调。为了研究SrrAB的调控功能，构建了一个srrA缺失突变体（ΔsrrA）。在体外和体内，在好氧和微好氧条件下，删除导致生长迟缓，并废除生物膜的形成。与减少的生物膜形成相关，ΔsrrA突变体产生更少的多糖细胞间粘附（PIA），并显示出降低的初始粘附能力。微阵列分析表明，srrA突变影响转录的230个基因在微氧条件下，和51个基因在好氧条件下。定量实时PCR证实了这一观察结果，并显示了通过支持细胞色素和喹啉氧化酶组装来维持电子传递链的基因的下调（例如，qoxB和ctaA）和厌氧代谢（例如，pflBA和nrdD）。在ΔsrrA突变体中，生物膜形成相关基因icaR的表达在好氧条件下上调，在微好氧条件下下调，而icaA在两种条件下均下调。电泳迁移率变动分析进一步揭示磷酸化的SrrA结合到icaR、icaA、qoxB和pflBA的启动子区以及其自身的启动子区。这些结果表明，在S。表皮生长因子SrrAB是一种自动调节因子，以ICA依赖性方式调节生物膜形成。在有氧条件下，SrrAB通过正向调节qoxBACD转录来调节电子传递链活性。在微需氧条件下，它通过调节pfl操纵子和nrdDG的表达来调节发酵过程和DNA合成。
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.