FlrA Represses Transcription of the Biofilm-Associated bpfA Operon in Shewanella putrefaciens
FlrA Represses Transcription of the Biofilm-Associated bpfA Operon in Shewanella putrefaciens
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FlrA 抑制腐败希瓦氏菌中生物膜相关 bpfA 操纵子的转录
DOI：
10.1128/aem.02410-16
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发表时间：
2017-02-01
影响因子：
4.4
通讯作者：
Xiao, Ya-Zhong
中科院分区：
文献类型：
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作者：
Cheng, Yuan-Yuan;Wu, Chao;Xiao, Ya-Zhong
希瓦氏菌生物膜形成的调控有利于工业和环境生物技术的应用。 BpfA 是一种粘附素，主要负责许多希瓦氏菌属物种的生物膜形成。然而，BpfA 产生和产生的生物膜的机制仍不清楚。我们之前描述了在有氧生长下 BpfA 表达被 DosD（一种氧刺激的二鸟苷酸环化酶）增强的发现。在目前的工作中，我们通过转座子诱变将 FlrA 鉴定为 Shewanella putrefaciens CN32 中 bpfA 操纵子的关键转录调节因子。 FlrA 通过结合与 -70 识别的 -10 和 -35 位点重叠的两个框来充当操纵子启动子的阻遏物。 bpfA 操纵子表达的 DosD 调节由 FlrA 介导，环二鸟苷酸 (c-di-GMP) 消除了 FlrA 与操纵子启动子的结合。我们还证明，鞭毛合成的辅助蛋白 FlhG 可以拮抗 FlrA 对 bpfA 操纵子表达的抑制。总的来说，这项工作表明，在腐烂链球菌 CN32 中，FlrA 在从 c-di-GMP 到 BpfA 相关生物膜形成的信号通路中充当中心介质。 重要性 运动性和生物膜是相互排斥的生活方式，两者之间的转变受到细菌试图适应不同环境条件波动的严格调节。已知许多细菌中的 FlrA 蛋白作为鞭毛合成的主要调节因子来控制运动。这项工作通过响应 c-di-GMP 控制腐烂链球菌 CN32 中粘附素 BpfA 的表达，阐明了其对生物膜形成的影响。因此，FlrA 在控制腐败链球菌 CN32 的运动和生物膜形成方面发挥双重作用。 flrA、bpfA 和 bpfA 操纵子启动子区域中的 FlrA 盒在不同希瓦氏菌菌株中同时出现，表明 bpfA 是控制该细菌物种中生物膜形成的常见机制。
Manipulation of biofilm formation in Shewanella is beneficial for application to industrial and environmental biotechnology. BpfA is an adhesin largely responsible for biofilm formation in many Shewanella species. However, the mechanism underlying BpfA production and the resulting biofilm remains vaguely understood. We previously described the finding that BpfA expression is enhanced by DosD, an oxygen-stimulated diguanylate cyclase, under aerobic growth. In the present work, we identify FlrA as a critical transcription regulator of the bpfA operon in Shewanella putrefaciens CN32 by transposon mutagenesis. FlrA acted as a repressor of the operon promoter by binding to two boxes overlapping the -10 and -35 sites recognized by -70. DosD regulation of the expression of the bpfA operon was mediated by FlrA, and cyclic diguanylic acid (c-di-GMP) abolished FlrA binding to the operon promoter. We also demonstrate that FlhG, an accessory protein for flagellum synthesis, antagonized FlrA repression of the expression of the bpfA operon. Collectively, this work demonstrates that FlrA acts as a central mediator in the signaling pathway from c-di-GMP to BpfA-associated biofilm formation in S. putrefaciens CN32.IMPORTANCE Motility and biofilm are mutually exclusive lifestyles, shifts between which are under the strict regulation of bacteria attempting to adapt to the fluctuation of diverse environmental conditions. The FlrA protein in many bacteria is known to control motility as a master regulator of flagellum synthesis. This work elucidates its effect on biofilm formation by controlling the expression of the adhesin BpfA in S. putrefaciens CN32 in response to c-di-GMP. Therefore, FlrA plays a dual role in controlling motility and biofilm formation in S. putrefaciens CN32. The cooccurrence of flrA, bpfA, and the FlrA box in the promoter region of the bpfA operon in diverse Shewanella strains suggests that bpfA is a common mechanism that controls biofilm formation in this bacterial species.