Repoila F, Majdalani N, Gottesman S
UMR960 INRA - ENVT, Laboratoire de Microbiologie Moléculaire, 23 Chemin des Capelles, 31076 Toulouse Cedex, France.
Mol Microbiol. 2003 May;48(4):855-61. doi: 10.1046/j.1365-2958.2003.03454.x.
Adaptation to the changing environment requires both the integration of external signals and the co-ordination of internal responses. Around 50 non-coding small RNAs (sRNAs) have been described in Escherichia coli; the levels of many of these vary with changing environmental conditions. This suggests that they play a role in cell adaptation. In this review, we use the regulation of RpoS (sigma38) translation as a paradigm of sRNA-mediated response to environmental conditions; rpoS is currently the only known gene regulated post-transcriptionally by at least three sRNAs. DsrA and RprA stimulate RpoS translation in response to low temperature and cell surface stress, respectively, whereas OxyS represses RpoS translation in response to oxidative shock. However, in addition to regulating RpoS translation, DsrA represses the translation of HNS (a global regulator of gene expression), whereas OxyS represses the translation of FhlA (a transcriptional activator), allowing the cell to co-ordinate different pathways involved in cell adaptation. Environmental cues affect the synthesis and stability of specific sRNAs, resulting in specific sRNA-dependent translational control.
适应不断变化的环境既需要整合外部信号，也需要协调内部反应。在大肠杆菌中已发现约50种非编码小RNA（sRNA）；其中许多的水平会随环境条件的变化而改变。这表明它们在细胞适应过程中发挥作用。在本综述中，我们以RpoS（σ38）翻译的调控作为sRNA介导的对环境条件反应的范例；rpoS是目前已知的唯一一个在转录后受至少三种sRNA调控的基因。DsrA和RprA分别在低温和细胞表面应激反应中刺激RpoS翻译，而OxyS在氧化应激反应中抑制RpoS翻译。然而，除了调控RpoS翻译外，DsrA还抑制HNS（一种基因表达的全局调控因子）的翻译，而OxyS抑制FhlA（一种转录激活因子）的翻译，从而使细胞能够协调参与细胞适应的不同途径。环境信号影响特定sRNA的合成和稳定性，从而导致特定的依赖sRNA的翻译控制。
