BpsR Modulates Bordetella Biofilm Formation by Negatively Regulating the Expression of the Bps Polysaccharide
BpsR Modulates Bordetella Biofilm Formation by Negatively Regulating the Expression of the Bps Polysaccharide
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DOI：
10.1128/jb.06020-11
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发表时间：
2012-01-01
影响因子：
3.2
通讯作者：
Deora, Rajendar
中科院分区：
文献类型：
--
作者：
Conover, Matt S.;Redfern, Crystal J.;Deora, Rajendar
博德特氏菌是动物、鸟类和人类的革兰氏阴性呼吸道病原体。一些博德特氏菌物种的一个标志性特征是即使在接种疫苗后它们也能够在呼吸道中有效存活。支气管败血博德特氏菌和百日咳博德特氏菌在非生物表面和小鼠呼吸道中形成生物膜。 Bps 胞外多糖是生物膜形成和博德特氏菌在小鼠呼吸道中存活的关键决定因素之一。为了更好地了解生物膜形成的调节，我们试图研究博德特氏菌中控制 Bps 表达的机制。与浮游生长的细胞中的水平相比，生物膜中 bpsABCD (bpsA-D) 的表达升高。我们发现 bpsA-D 的表达独立于 BvgAS。随后，我们鉴定了一个开放阅读框（ORF）BB1771（此处指定为bpsR），它位于bpsA-D基因座的上游且方向相反。 BpsR 与 MarR 转录调节因子家族同源。对野生型和 Delta bpsR 菌株的 bpsA 和 bpsD 转录物以及 Bps 多糖水平的测量表明，BpsR 具有阻遏蛋白的功能。与 Bps 产量的增加相一致，bpsR 突变体表现出更加结构化的生物膜。我们绘制了 bpsA-D 启动子区域图谱，并显示纯化的 BpsR 蛋白与 bpsA-D 启动子特异性结合。我们的结果为博德特氏菌用于控制 Bps 多糖的产生和生物膜形成的调控策略提供了机制见解。
Bordetella bacteria are Gram-negative respiratory pathogens of animals, birds, and humans. A hallmark feature of some Bordetella species is their ability to efficiently survive in the respiratory tract even after vaccination. Bordetella bronchiseptica and Bordetella pertussis form biofilms on abiotic surfaces and in the mouse respiratory tract. The Bps exopolysaccharide is one of the critical determinants for biofilm formation and the survival of Bordetella in the murine respiratory tract. In order to gain a better understanding of regulation of biofilm formation, we sought to study the mechanism by which Bps expression is controlled in Bordetella. Expression of bpsABCD (bpsA-D) is elevated in biofilms compared with levels in planktonically grown cells. We found that bpsA-D is expressed independently of BvgAS. Subsequently, we identified an open reading frame (ORF), BB1771 (designated here bpsR), that is located upstream of and in the opposite orientation to the bpsA-D locus. BpsR is homologous to the MarR family of transcriptional regulators. Measurement of bpsA and bpsD transcripts and the Bps polysaccharide levels from the wild-type and the Delta bpsR strains suggested that BpsR functions as a repressor. Consistent with enhanced production of Bps, the bpsR mutant displayed considerably more structured biofilms. We mapped the bpsA-D promoter region and showed that purified BpsR protein specifically bound to the bpsA-D promoter. Our results provide mechanistic insights into the regulatory strategy employed by Bordetella for control of the production of the Bps polysaccharide and biofilm formation.