Multiple promoters control expression of the Yersinia enterocolitica phage-shock-protein A (pspA) operon.
Multiple promoters control expression of the Yersinia enterocolitica phage-shock-protein A (pspA) operon.
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DOI：
10.1099/mic.0.28714-0
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发表时间：
2006-04
期刊：
影响因子：
1.5
通讯作者：
Michelle E. Maxson;A. Darwin
中科院分区：
文献类型：
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作者：
Michelle E. Maxson;A. Darwin
广泛保守的噬菌体休克蛋白A(PSPA)操纵子编码对小肠结肠炎耶尔森氏菌毒力至关重要的胞外应激反应系统，并与大肠杆菌、肠沙门氏菌和福氏志贺氏菌的其他重要表型相关联。PSPA操纵子表达的调节是通过PSPA上游的启动子介导的，该启动子依赖于Sigma因子RpoN(Sigma(54))和增强子结合蛋白PspF。PSPA、PSPB和PSPC编码在PSPA操纵子中，也通过参与可能调节PspF活性的信号转导途径来调节表达。所有这些表明，PSPA操纵子的适当表达是至关重要的。先前对小肠结肠炎耶尔森菌PSPA操纵子的遗传分析表明，一些PSP基因的表达可能不依赖于PspF/RpoN，从而导致了额外水平的复杂性。在这里，rpoN零突变和插入子分析被用来证实PspF/RpoN非依赖的基因表达确实起源于PSP基因座。采用分子遗传学方法对PSP基因座内的两个大的非编码区进行了系统分析。通过引物延伸、控制区缺失和定点突变实验，鉴定了PSPA上游和下游的RpoN非依赖性启动子。还确定了PSPA上游依赖于PspF/RpoN的启动子的准确位置。这些RpoN非依赖启动子的发现揭示了小肠结肠炎耶尔森菌PSPA操纵子的转录复杂性，该操纵子可能在某些条件下允许PSP基因的低水平结构性表达和/或额外的调节。
The widely conserved phage-shock-protein A (pspA) operon encodes an extracytoplasmic stress response system that is essential for virulence in Yersinia enterocolitica, and has been linked to other important phenotypes in Escherichia coli, Salmonella enterica and Shigella flexneri. Regulation of pspA operon expression is mediated through a promoter upstream of pspA that depends on sigma factor RpoN (sigma(54)) and the enhancer binding protein PspF. PspA, PspB and PspC, encoded within the pspA operon, also regulate expression by participating in a putative signal transduction pathway that probably serves to modulate PspF activity. All of this suggests that appropriate expression of the pspA operon is critical. Previous genetic analysis of the Y. enterocolitica pspA operon suggested that an additional level of complexity might be mediated by PspF/RpoN-independent expression of some psp genes. Here, an rpoN null mutation and interposon analysis were used to confirm that PspF/RpoN-independent gene expression does originate within the psp locus. Molecular genetic approaches were used to systematically analyse the two large non-coding regions within the psp locus. Primer extension, control region deletion and site-directed mutagenesis experiments led to the identification of RpoN-independent promoters both upstream and downstream of pspA. The precise location of the PspF/RpoN-dependent promoter upstream of pspA was also determined. The discovery of these RpoN-independent promoters reveals yet another level of transcriptional complexity for the Y. enterocolitica pspA operon that may function to allow low-level constitutive expression of psp genes and/or additional regulation under some conditions.