Hengge-Aronis R
Institute of Plant Physiology and Microbiology, Department of Biology, Free University of Berlin, Königin-Luise-Str 12-16a, 14195, Berlin, Germany.
Curr Opin Microbiol. 1999 Apr;2(2):148-52. doi: 10.1016/S1369-5274(99)80026-5.
Under various stress conditions, two sigma subunits of RNA polymerase, sigmaS and sigma70, coexist in Escherichia coli cells. In contrast to sigma70, sigmaS is subject to intricate regulation and coordinates an emergency reaction to stress as well as long term stress adaptation. In vivo, the two sigma factors clearly control different genes. Yet, they are structurally and functionally very similar and basically recognize the same promoter sequences. Recent data suggest that sigma factor specificity at stress-activated promoters is affected by the interplay of the two RNA polymeraseholoenzymes with additional regulatory factors, such as H-NS, Lrp, CRP, IHF or Fis, that differentially affect transcription initiation by sigmaS or sigma70 in a promoter-specific manner.
在各种应激条件下，RNA聚合酶的两个σ亚基，即σS和σ70，共存于大肠杆菌细胞中。与σ70不同，σS受到复杂的调控，并协调对应激的应急反应以及长期应激适应。在体内，这两种σ因子明显控制不同的基因。然而，它们在结构和功能上非常相似，并且基本上识别相同的启动子序列。最近的数据表明，应激激活启动子处的σ因子特异性受到两种RNA聚合酶全酶与其他调控因子（如H-NS、Lrp、CRP、IHF或Fis）相互作用的影响，这些调控因子以启动子特异性方式差异性地影响σS或σ70的转录起始。
