Polynucleotide phosphorylase independently controls virulence factor expression levels and export in Yersinia spp.
Polynucleotide phosphorylase independently controls virulence factor expression levels and export in Yersinia spp.
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DOI：
10.1111/j.1574-6968.2007.00689.x
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发表时间：
2007-05-01
影响因子：
2.1
通讯作者：
Schesser, Kurt
中科院分区：
文献类型：
--
作者：
Rosenzweig, Jason A.;Chromy, Brett;Schesser, Kurt
先前的研究表明，在细胞培养感染试验中，耶尔森菌III型分泌系统（T3SS）的最佳功能需要外核糖核酸酶多核苷酸磷酸化酶（PNPase），并且通过表达PNPase的类似70-aa S1 rna结合结构域，可以在Delta pnp菌株中恢复正常的T3SS活性。本研究表明，与等基因野生型菌株相比，三角洲耶尔森菌pnp菌株对小鼠的毒力较弱。为了开始了解在缺乏PNPase的情况下限制T3SS活性的原因，我们分析了三角洲耶尔森菌pnp菌株中T3SS编码转录物和蛋白质。令人惊讶的是，与野生型菌株相比，Delta pnp耶尔森菌菌株具有更高水平的t3ss编码转录物和蛋白质。然后，我们发现含有rna结合子结构域中断的S1变体在恢复正常T3SS活性方面是无活性的。然而，T3SS表达水平在表达活性和非活性S1蛋白的Delta pnp菌株之间没有差异，进一步表明T3SS活性和表达水平，至少与PNPase及其S1结构域相关，没有联系。结果表明，PNPase通过不同的机制影响T3SS的表达和活性，并且s1依赖性对T3SS活性的影响涉及RNA中间体。
Previously, it was shown that optimal functioning of the Yersinia type III secretion system (T3SS) in cell culture infection assays requires the exoribonuclease polynucleotide phosphorylase (PNPase) and that normal T3SS activity could be restored in the Delta pnp strains by expressing just the similar to 70-aa S1 RNA-binding domain of PNPase. Here, it is shown that the Yersinia Delta pnp strain is less virulent in the mouse compared with the isogenic wild-type strain. To begin to understand what could be limiting T3SS activity in the absence of PNPase, T3SS-encoding transcripts and proteins in the Yersinia Delta pnp strains were analyzed. Surprisingly, it was found that the Delta pnp Yersinia strains possessed enhanced levels of T3SS-encoding transcripts and proteins compared with the wild-type strains. We then found that an S1 variant containing a disruption in its RNA-binding subdomain was inactive in terms of restoring normal T3SS activity. However, T3SS expression levels did not differ between Delta pnp strains expressing active and inactive S1 proteins, further showing that T3SS activity and expression levels, at least as related to PNPase and its S1 domain, are not linked. The results suggest that PNPase affects the expression and activity of the T3SS by distinct mechanisms and that the S1-dependent effect on T3SS activity involves an RNA intermediate.