Laboratory of Molecular Biology, National Cancer Institute, Center for Cancer Research, Bethesda, MD, USA.
EMBO J. 2010 Sep 15;29(18):3094-107. doi: 10.1038/emboj.2010.179. Epub 2010 Aug 3.
The alternative sigma factor RpoS responds to multiple stresses and activates a large number of genes that allow bacteria to adapt to changing environments. The accumulation of RpoS is regulated at multiple levels, including the regulation of its translation by small regulatory RNAs (sRNAs). A library of plasmids expressing each of 26 Escherichia coli sRNAs that bind Hfq was created to globally and rapidly analyse regulation of an rpoS-lacZ translational fusion. The approach can be easily applied to any gene of interest. When overexpressed, four sRNAs, including OxyS, previously shown to repress rpoS, were observed to repress the expression of the rpoS-lacZ fusion. Along with DsrA and RprA, two previously defined activators of rpoS translation, a third new sRNA activator, ArcZ, was identified. The expression of arcZ is repressed by the aerobic/anaerobic-sensing ArcA-ArcB two-component system under anaerobic conditions and adds translational regulation to the ArcA-ArcB regulon. ArcZ directly represses, and is repressed by, arcB transcription, providing a negative feedback loop that may affect functioning of the ArcA-ArcB regulon.
替代 sigma 因子 RpoS 响应多种应激，并激活大量基因，使细菌能够适应不断变化的环境。RpoS 的积累受到多个层次的调节，包括其翻译由小调控 RNA（sRNA）的调节。创建了一个表达与 Hfq 结合的 26 种大肠杆菌 sRNA 中的每一种的质粒文库，以全局和快速地分析 rpoS-lacZ 翻译融合物的调节。该方法可以轻松应用于任何感兴趣的基因。当过度表达时，观察到四个以前显示抑制 rpoS 的 sRNA，包括 OxyS，抑制 rpoS-lacZ 融合物的表达。与 DsrA 和 RprA 一起，鉴定了第三个新的 sRNA 激活子 ArcZ，它是 rpoS 翻译的先前定义的激活子。ArcZ 的表达受有氧/厌氧感应 ArcA-ArcB 双组分系统在厌氧条件下抑制，并且向 ArcA-ArcB 调控物添加翻译调节。ArcZ 直接抑制 arcB 转录，并受其抑制，提供可能影响 ArcA-ArcB 调控物功能的负反馈回路。
