Analysis of the Yersinia enterocolitica PspBC proteins defines functional domains, essential amino acids and new roles within the phage-shock-protein response.
Analysis of the Yersinia enterocolitica PspBC proteins defines functional domains, essential amino acids and new roles within the phage-shock-protein response.
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DOI：
10.1111/j.1365-2958.2009.06885.x
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发表时间：
2009-11
影响因子：
3.6
通讯作者：
Darwin AJ
中科院分区：
文献类型：
--
作者：
Gueguen E;Savitzky DC;Darwin AJ
小肠结肠炎耶尔森氏菌噬菌体休克蛋白（Psp）应激反应系统被蛋白质输出系统的错误定位外膜分泌素组分激活，并对毒力至关重要。细胞质膜蛋白PspB和PspC被认为是该系统的双重功能组分，既作为psp基因表达的正调节因子，又在分泌素诱导的应激期间支持存活。在这项研究中，我们解开了PspBC的调节和生理功能，并发现了意想不到的新角色，功能结构域和必需氨基酸。首先，我们发现PspB通过转录前和转录后机制控制PspC浓度。然后，我们筛选具有改变的转录调节功能的PspBC突变体。出乎意料的是，我们发现PspB和PspC突变体，激活psp基因表达的分泌素诱导的压力的情况下。连同随后的截短分析，这揭示了PspC胞质结构域在负调节psp基因表达中起着不可预见的作用。相反，PspC周质结构域内的突变废除了其激活psp基因表达的能力。值得注意的是，不能激活psp基因表达的PspC突变体保留了它们在分泌素诱导的应激期间支持存活的能力。这些数据有力地支持了这两个功能是独立的这一提议。
The Yersinia enterocolitica phage-shock-protein (Psp) stress response system is activated by mislocalized outer membrane secretin components of protein export systems and is essential for virulence. The cytoplasmic membrane proteins PspB and PspC were proposed to be dual function components of the system, acting both as positive regulators of psp gene expression and to support survival during secretin-induced stress. In this study we have uncoupled the regulatory and physiological functions of PspBC and discovered unexpected new roles, functional domains and essential amino acids. First, we showed that PspB controls PspC concentration by both pre- and post-transcriptional mechanisms. We then screened for PspBC mutants with altered transcriptional regulatory function. Unexpectedly, we identified PspB and PspC mutants that activated psp gene expression in the absence of secretin-induced stress. Together with a subsequent truncation analysis, this revealed that the PspC cytoplasmic domain plays an unforeseen role in negatively regulating psp gene expression. Conversely, mutations within the PspC periplasmic domain abolished its ability to activate psp gene expression. Significantly, PspC mutants unable to activate psp gene expression retained their ability to support survival during secretin-induced stress. These data provide compelling support for the proposal that these two functions are independent.
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