Inhibition of Escherichia coli RNA polymerase by bacteriophage T4 AsiA.
Inhibition of Escherichia coli RNA polymerase by bacteriophage T4 AsiA.
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噬菌体 T4 AsiA 对大肠杆菌 RNA 聚合酶的抑制。
DOI：
10.1006/jmbi.1998.1742
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Darst,SA
中科院分区：
文献类型：
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作者：
Severinova,E;Severinov,K;Darst,SA
10 kDa噬菌体T4 antisigma蛋白AsiA以高亲和力结合大肠杆菌RNA聚合酶启动子特异性亚基σ70，并抑制其转录活性。AsiA主要通过与σ 70保守区4.2的相互作用与σ 70结合，该保守区也参与了−35共有启动子元件的序列特异性识别。我们发现AsiA与核心RNA聚合酶（RNAP）和σ 70形成稳定的三元复合物，因此不会通过阻止其与核心RNAP结合而抑制σ 70的活性。我们研究了AsiA对两个−10/−35型启动子和两个“扩展的−10”启动子的开放启动子复合物形成和失败启动的影响。我们的结果表明，AsiA与σ 70的结合和σ 70区域4.2与−10/−35启动子的−35共有启动子元件的相互作用是相互排斥的。相比之下，AsiA对开放启动子复合物的形成和从延伸的-10启动子的失败启动的影响要小得多，延伸的-10启动子缺乏-35共有元件并且不需要σ 70保守区4.2。从这些结果我们得出结论，T4 AsiA抑制E.通过干扰σ 70保守区4.2和−35共有启动子元件之间的相互作用，在−10/−35启动子上实现了大肠杆菌RNAP σ 70全酶的转录。
The 10 kDa bacteriophage T4 antisigma protein AsiA binds the Escherichia coli RNA polymerase promoter specificity subunit, σ70, with high affinity and inhibits its transcription activity. AsiA binds to σ70primarily through an interaction with σ70conserved region 4.2, which has also been implicated in sequence-specific recognition of the −35 consensus promoter element. Here we show that AsiA forms a stable ternary complex with core RNA polymerase (RNAP) and σ70and thus does not inhibit σ70activity by preventing its binding to core RNAP. We investigated the effect of AsiA on open promoter complex formation and abortive initiation at two −10/−35 type promoters and two “extended −10” promoters. Our results indicate that the binding of AsiA to σ70and the interaction of σ70region 4.2 with the −35 consensus promoter element of −10/−35 promoters is mutually exclusive. In contrast, AsiA has much less effect on open promoter complex formation and abortive initiation from extended −10 promoters, which lack a −35 consensus element and do not require σ70conserved region 4.2. From these results we conclude that T4 AsiA inhibits E. coli RNAP σ70holoenzyme transcription at −10/−35 promoters by interfering with the required interaction between σ70conserved region 4.2 and the −35 consensus promoter element.