Evidence that Bacillus catabolite control protein CcpA interacts with RNA polymerase to inhibit transcription
Evidence that Bacillus catabolite control protein CcpA interacts with RNA polymerase to inhibit transcription
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DOI：
10.1111/j.1365-2958.2005.04496.x
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发表时间：
2005-04-01
影响因子：
3.6
通讯作者：
Chambliss, GH
中科院分区：
文献类型：
--
作者：
Kim, JH;Yang, YK;Chambliss, GH
芽孢杆菌分解代谢控制蛋白(CCPA)通过与分解代谢反应元件(Cres)启动子内外的相互作用来调控分解代谢反应(CR)基因或操纵子的表达，从而介导碳分解代谢抑制(CCR)。在这里，我们研究了CCPA如何在体外抑制CR启动子的转录。CCPA对不同的Cre有不同的亲和力，但这与其抑制转录的能力无关。在AmyE启动子中，它与CCPA结合位点(Amye cre中心位于+4.5)重叠，CCPA不能阻止RNA聚合酶(RNAP)与启动子的结合；它甚至可能与RNAP相互作用。在Amye启动子(-10个六角体)和Amye cre之间插入非整数螺旋(1.5和2.5)可以减轻Ccr的Amye表达。在XYL操纵子中，尽管其cre的下游位置(一个主要的cre集中在+130.5)，但ccpA阻止了转录起始，而不是cre位置的延伸(障碍)。综上所述，我们的结果强烈表明，CCPA需要与RNAP相互作用来抑制转录。
Bacillus catabolite control protein (CcpA) mediates carbon catabolite repression (CCR) by controlling expression of catabolite responsive (CR) genes or operons through interaction with catabolite responsive elements (cres) located within or outside of CR promoters. Here, we investigated how CcpA inhibits the transcription of CR promoters in vitro. CcpA has different affinities for different cres, but this does not correlate with its ability to inhibit transcription. In the amyE promoter, which overlaps a CcpA binding site (amyE cre centred at +4.5), CcpA does not prevent RNA polymerase (RNAP) binding to the promoter; it may even interact with RNAP. Inserting non-integral turns of helix (1.5 and 2.5) between the amyE promoter (-10 hexamer) and the amyE cre relieved CCR of amyE expression. In the xyl operon, despite the downstream location of its cre (a major cre centred at +130.5), CcpA blocked transcription initiation, not elongation (roadblock) at the site of the cre. Taken together, our results strongly suggest that CcpA requires interactions with RNAP to inhibit transcription.