The bacteriophage T4 AsiA protein: a molecular switch for sigma 70 dependent promoters
The bacteriophage T4 AsiA protein: a molecular switch for sigma 70 dependent promoters
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DOI：
10.1046/j.1365-2958.1998.00729.x
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发表时间：
1998-02-01
影响因子：
3.6
通讯作者：
Kolb, A
中科院分区：
文献类型：
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作者：
Colland, F;Orsini, G;Kolb, A
由噬菌体T4编码的Asia蛋白在细菌和早期噬菌体启动子上抑制依赖于E sigma(70)的转录。我们证明ASIA的抑制作用涉及干扰宿主RNA聚合酶对-35共识启动子序列的识别。体外实验是用C末端标记的Sigma因子进行的，该因子能够进行功能上的全酶重组。通过蛋白酶和羟基自由基蛋白足迹，我们发现亚洲与识别-35序列的sigma(70)的4.2区域结合。两个平行实验支持对该基因启动子识别的直接干扰。含有全酶的固定相Sigma因子可以在缺乏a-35区域的启动子上启动转录，对亚洲的抑制不敏感。E sigma(70)对GalP1启动子的识别不受亚洲存在的影响。因此，我们得出结论，ASIA通过用-35六聚体抵消Sigma(70)4.2区域的识别来抑制大肠杆菌和T4早期启动子的转录。
The AsiA protein, encoded by bacteriophage T4, inhibits E sigma(70)-dependent transcription at bacterial and early-phage promoters. We demonstrate that the inhibitory action of AsiA involves interference with the recognition of the -35 consensus promoter sequence by host RNA polymerase. In vitro experiments were performed with a C-terminally labelled sigma factor that is competent for functional holoenzyme reconstitution. By protease and hydroxyl radical protein footprinting, we show that AsiA binds region 4.2 of sigma(70), which recognizes the -35 sequence. Direct interference with the recognition of the promoter at this locus is supported by two parallel experiments. The stationary-phase sigma factor containing holoenzyme, which can initiate transcription at promoters devoid of a -35 region, is insensitive to AsiA inhibition. The recognition of a galP1 promoter by E sigma(70) is not affected by the presence of AsiA. Therefore, we conclude that AsiA inhibits transcription from Escherichia coli and T4 early promoters by counteracting the recognition of region 4.2 of sigma(70) with the -35 hexamer.