CORE RNA-POLYMERASE ASSISTS BINDING OF THE TRANSCRIPTION FACTOR SIGMA(54) TO PROMOTER DNA
CORE RNA-POLYMERASE ASSISTS BINDING OF THE TRANSCRIPTION FACTOR SIGMA(54) TO PROMOTER DNA
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DOI：
10.1111/j.1365-2958.1993.tb01573.x
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发表时间：
1993-04-01
影响因子：
3.6
通讯作者：
BUCK, M
中科院分区：
文献类型：
--
作者：
CANNON, W;CLAVERIEMARTIN, F;BUCK, M
细菌RNA聚合酶的σ亚基对于RNA聚合酶全酶与启动子DNA的特异性结合是必需的。与含有 sigma54 的全酶形成的启动子复合物保持为闭合复合物，除非它们被一类增强子结合蛋白激活。在缺乏核心RNA聚合酶亚基的情况下，sigma54转录因子可以特异性结合到某些启动子位点。这一特性证明了核心聚合酶在转录中的新作用，即它有助于 sigma54 与启动子 DNA 的结合。 sigma54 的氨基末端区域缺失的改变形式显示出对特定 DNA 结合位点的亲和力增加。尽管能够与核心RNA聚合酶复合，但突变体sigma54未能通过改变其足迹以野生型sigma54特有的方式对核心聚合酶做出反应。该结果表明sigma54具有潜在的DNA结合活性，该活性由核心RNA聚合酶揭示，并且可能涉及sigma54构象的变化。与sigma54-全酶形成的启动子复合物似乎在性质上不同，这取决于靶启动子序列，表明不同的可激活复合物在不同的启动子序列处形成。
The sigma subunit of bacterial RNA polymerase is necessary for the specific binding of RNA polymerase holoenzyme to promoter DNA. Promoter complexes which form with holoenzyme containing sigma54 remain as closed complexes unless they are activated by one class of enhancer binding protein. The sigma54 transcription factor can bind specifically to certain promoter sites in the absence of the core RNA polymerase subunits. This property has allowed demonstration of a new role for core polymerase in transcription, namely that it assists the binding of sigma54 to promoter DNA. An altered form of sigma54 with a deletion within the amino-terminal region showed increased affinity for specific DNA-binding sites. Although able to complex with core RNA polymerase the mutant sigma54 failed to respond to core polymerase in the manner characteristic of the wild-type sigma54 by altering its footprint. This result indicates that sigma54 has a latent DNA-binding activity which is revealed by core RNA polymerase, and possibly involves a change in sigma54 conformation. Promoter complexes which formed with sigma54 -holoenzyme appeared to be qualitatively different, depending upon the target promoter sequence, suggesting that different activatable complexes form at different promoter sequences.