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首页> 外文期刊>Journal of bacteriology >Promoter Strength Properties of the Complete Sigma E Regulon of Escherichia coli and Salmonella enterica
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Promoter Strength Properties of the Complete Sigma E Regulon of Escherichia coli and Salmonella enterica

机译：大肠埃希菌和沙门氏菌的完整Sigma E调节子的启动子强度特性

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The σE-directed envelope stress response maintains outer membrane homeostasis and is an important virulence determinant upon host infection in Escherichia coli and related bacteria. σE is activated by at least two distinct mechanisms: accumulation of outer membrane porin precursors and an increase in the alarmone ppGpp upon transition to stationary phase. Expression of the σE regulon is driven from a suite of approximately 60 σE-dependent promoters. Using green fluorescent protein fusions to each of these promoters, we dissected promoter contributions to the output of the regulon under a variety of in vivo conditions. We found that the σE promoters exhibit a large dynamic range, with a few strong and many weak promoters. Interestingly, the strongest promoters control either transcriptional regulators or functions related to porin homeostasis, the very functions conserved among E. coli and its close relatives. We found that (i) the strength of most promoters is significantly affected by the presence of the upstream (?35 to ?65) region of the promoter, which encompasses the UP element, a binding site for the C-terminal domain of the α-subunit of RNA polymerase; (ii) ppGpp generally activates σE promoters, and (iii) σE promoters are responsive to changing σE holoenzyme levels under physiological conditions, reinforcing the idea that the σE regulon is extremely dynamic, enabling cellular adaptation to a constantly changing environment.
机译：σ E 定向的包膜应力反应维持了外膜稳态，并且是宿主感染大肠杆菌和相关细菌的重要毒力决定因素。至少通过两种不同的机制激活σ E ：外膜孔蛋白前体的积累和过渡到固定相时警报蛋白ppGpp的增加。 σ E 调节子的表达是由大约60个依赖σ E 的启动子组成的。使用绿色荧光蛋白融合到每个这些启动子，我们解剖启动子在各种体内条件下对调节子输出的贡献。我们发现σ E 启动子表现出较大的动态范围，有几个强启动子和许多弱启动子。有趣的是，最强的启动子控制转录调节子或与孔蛋白稳态相关的功能，而这些功能在E中是保守的。大肠菌及其近亲。我们发现（i）大多数启动子的强度受启动子上游（？35至？65）区域的影响，该区域包含UP元素，即α的C端结构域的结合位点-RNA聚合酶的亚基; （ii）ppGpp通常会激活σ E 启动子，并且（iii）σ E 启动子在生理条件下对σ E 全酶水平的变化有反应，强化了σ E 调节子非常动态的想法，使细胞能够适应不断变化的环境。

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