Involvement of RNA-binding protein Hfq in the post-transcriptional regulation of invE gene expression in Shigella sonnei
Involvement of RNA-binding protein Hfq in the post-transcriptional regulation of invE gene expression in Shigella sonnei
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DOI：
10.1074/jbc.m710108200
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发表时间：
2008-02-29
影响因子：
4.8
通讯作者：
Watanabe, Haruo
中科院分区：
文献类型：
--
作者：
Mitobe, Jiro;Morita-Ishihara, Tomoko;Watanabe, Haruo
志贺氏菌毒力基因的温度依赖性调节被认为是在转录阶段由调节因子 VirF 和 InvE 完成的。本文描述的几条证据表明，InvE 表达的转录后调节在毒力基因表达的温度依赖性调节中起着关键作用：（i）相当数量的 invE mRNA 在低温条件下继续转录，其中 InvE 蛋白的产生受到严格抑制； (ii) invE mRNA的稳定性显着降低，因为在抑制条件下其衰减率显着增加。引人注目的是，在宋内志贺氏菌的 hfq 突变体中，即使在低温下也能产生大量的 InvE 蛋白。研究发现 InvE 水平的增加与 invE mRNA 稳定性的提高有关，这与 RNA 伴侣 Hfq 影响各种基因的转录后调控的发现一致。一致的是，即使在 37°C 的表达条件下，Hfq 蛋白的过表达也会减少 InvE 蛋白的产生。在凝胶位移分析和表面等离振子共振 (Biacore) 分析这两个实验中，纯化的 Hfq 蛋白与 invE RNA 的体外结合在 30°C 下比在 37°C 下更强。这些结果共同表明，Hfq 在转录后步骤中 invE 表达的温度依赖性调节中发挥着重要作用。
The temperature-dependent regulation of Shigella virulence genes is believed to be accomplished at the transcriptional stage by the regulators VirF and InvE. Several lines of evidence herein described indicate that post-transcriptional regulation of InvE expression plays a key role in the temperature-dependent regulation of virulence gene expression: (i) a considerable amount of invE mRNA continues to be transcribed under low temperature conditions, where the production of InvE protein is tightly repressed; (ii) the stability of invE mRNA markedly decreases, because its decay rate is significantly increased under the repressing conditions. Strikingly, in the hfq mutant of Shigella sonnei, a considerable amount of InvE protein was produced even at low temperature. This increase in the InvE level was found to be associated with the improved stability of invE mRNA, in agreement with the finding that the RNA chaperon Hfq influences post-transcriptional regulations of various genes. Consistently, overexpression of the Hfq protein decreased the production of InvE protein even under the expressing condition at 37 degrees C. The binding in vitro of purified Hfq protein to invE RNA was shown to be stronger at 30 degrees C than at 37 degrees C in two experiments, gel shift analysis and surface plasmon resonance (Biacore) analysis. These results altogether suggest that Hfq plays an important role in the temperature-dependent regulation of invE expression at the post-transcriptional step.