Campbell Elizabeth A, Westblade Lars F, Darst Seth A
Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Curr Opin Microbiol. 2008 Apr;11(2):121-7. doi: 10.1016/j.mib.2008.02.016. Epub 2008 Mar 28.
In bacteria, sigma factors are essential for the promoter DNA-binding specificity of RNA polymerase. The sigma factors themselves are regulated by anti-sigma factors that bind and inhibit their cognate sigma factor, and 'appropriators' that deploy a particular sigma-associated RNA polymerase to a specific promoter class. Adding to the complexity is the regulation of anti-sigma factors by both anti-anti-sigma factors, which turn on sigma factor activity, and co-anti-sigma factors that act in concert with their partner anti-sigma factor to inhibit or redirect sigma activity. While sigma factor structure and function are highly conserved, recent results highlight the diversity of structures and mechanisms that bacteria use to regulate sigma factor activity, reflecting the diversity of environmental cues that the bacterial transcription system has evolved to respond.
在细菌中，σ因子对于RNA聚合酶与启动子DNA的结合特异性至关重要。σ因子本身受到抗σ因子的调控，抗σ因子会结合并抑制其同源σ因子，还有“适配体”，它们会将特定的与σ相关的RNA聚合酶部署到特定的启动子类别。使情况更为复杂的是，抗σ因子既受到开启σ因子活性的抗抗σ因子的调控，也受到与其伙伴抗σ因子协同作用以抑制或重定向σ活性的共抗σ因子的调控。虽然σ因子的结构和功能高度保守，但最近的研究结果凸显了细菌用于调控σ因子活性的结构和机制的多样性，这反映了细菌转录系统进化出的对环境线索做出反应的多样性。
