Ko D C, Marr M T, Guo J, Roberts J W
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853 USA.
Genes Dev. 1998 Oct 15;12(20):3276-85. doi: 10.1101/gad.12.20.3276.
The sigma initiation factor sigma70 of Escherichia coli acts not only in promoter recognition and DNA strand opening, but also to mediate the transformation of RNA polymerase (RNAP) to an antiterminating form by the phage lambda gene Q protein. Q is able to bind and modify RNAP when alpha70, still present in the initially elongating enzyme, recognizes a repeat of the -10 promoter element and induces a transcription pause. We have isolated mutations in the rpoD gene for sigma70 that impair Q function because they reduce the ability of sigma70 to recognize the downstream pause site. These mutations identify a locus of sigma70 that is important for the formation and stability of open promoter complex, likely because it mediates protein interactions with RNAP core.
大肠杆菌的σ起始因子σ70不仅在启动子识别和DNA链解旋中起作用,还介导RNA聚合酶(RNAP)被噬菌体λ基因Q蛋白转化为抗终止形式。当仍存在于最初延伸的酶中的α70识别-10启动子元件的重复序列并诱导转录暂停时,Q能够结合并修饰RNAP。我们已经分离出σ70的rpoD基因中的突变,这些突变损害了Q的功能,因为它们降低了σ70识别下游暂停位点的能力。这些突变确定了σ70的一个位点,该位点对于开放启动子复合物的形成和稳定性很重要,可能是因为它介导了与RNAP核心的蛋白质相互作用。