Kulbachinskiy A, Mustaev A, Goldfarb A, Nikiforov V
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow.
FEBS Lett. 1999 Jul 2;454(1-2):71-4. doi: 10.1016/s0014-5793(99)00778-4.
The promoter recognition site on the sigma70 initiation factor is shielded from interaction with DNA unless sigma70 is bound to the core component of RNA polymerase (RNAP). It is shown that interaction of sigma70 with the isolated beta' subunit of Escherichia coli RNAP is sufficient to induce unshielding of the DNA binding site. Using UV-induced DNA-protein cross-linking we demonstrate that free beta' stimulates specific cross-links between region 2 of the sigma70 polypeptide and a fragment of the non-template promoter strand containing the TATAAT sequence. Thus the sigmabeta' subassembly of RNAP can assume a functionally competent conformation independently of the bulk of the RNAP core.
除非σ70与RNA聚合酶(RNAP)的核心组分结合,否则σ70起始因子上的启动子识别位点会被屏蔽而无法与DNA相互作用。研究表明,σ70与大肠杆菌RNAP分离的β'亚基相互作用足以诱导DNA结合位点的去屏蔽。利用紫外线诱导的DNA-蛋白质交联,我们证明游离的β'会刺激σ70多肽的区域2与包含TATAAT序列的非模板启动子链片段之间形成特异性交联。因此,RNAP的σβ'亚组件可以独立于RNAP核心的大部分而呈现功能上的活性构象。