ALTERED PROMOTER RECOGNITION BY MUTANT FORMS OF THE SIGMA-70 SUBUNIT OF ESCHERICHIA-COLI RNA-POLYMERASE
ALTERED PROMOTER RECOGNITION BY MUTANT FORMS OF THE SIGMA-70 SUBUNIT OF ESCHERICHIA-COLI RNA-POLYMERASE
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DOI：
10.1016/0022-2836(89)90568-8
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发表时间：
1989-04-20
影响因子：
5.6
通讯作者：
GROSS, CA
中科院分区：
文献类型：
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作者：
SIEGELE, DA;HU, JC;GROSS, CA
我们使用 37 个突变型和野生型启动子的转录融合，系统地分析了 rpoD 中 13 个突变的体内启动子识别特性，rpoD 是编码大肠杆菌 RNA 聚合酶全酶 .sigma.70 亚基的基因。我们发现了三类rpoD突变：（1）表明σ70的氨基酸侧链与启动子中的特定碱基之间接触的突变； (2) 似乎影响与启动子 DNA 的序列独立接触或聚合酶异构化的突变； (3) 对启动子识别影响很小或没有影响的突变。我们的结果使我们建议，靠近σ70的C末端的序列（其与噬菌体和细菌DNA结合蛋白的螺旋-转角-螺旋DNA结合基序相似）负责识别-35区域，并且σ.70内部的序列位于σ中高度保守的区域中。因素，识别启动子的-10 区域。位于所提出的螺旋-转角-螺旋基序的识别螺旋中的 rpoD 突变影响与 -35 区域中特定碱基的相互作用，而上游螺旋中的突变（被认为与磷酸主链接触）对启动子识别具有序列无关的影响。
We have systematically assayed the in vivo promoter recognition properties of 13 mutations in rpoD, the gene that encodes the .sigma.70 subunit of Escherichia coli RNA polymerase holoenzyme, using transcriptional fusions to 37 mutant and wild-type promoters. We found three classes of rpoD mutations: (1) mutations that suggest contacts between amino acid side-chains of .sigma.70 and specific bases in the promoter; (2) mutations that appear to affect either sequence independent contacts to promoter DNA or isomerization of the polymerase; and (3) mutations that have little or no effect on promoter recognition. Our results lead us to suggest that a sequence near the C terminus of .sigma.70, which is similar to the helix-turn-helix DNA binding motif of phage and bacterial DNA binding proteins, is responsible for recognition of the -35 region, and that a sequence internal to .sigma.70, in a region which is highly conserved among .sigma. factors, recognizes the -10 region of the promoter. rpoD mutations that lie in the recognition helix of the proposed helix-turn-helix motif affect interactions with specific bases in the -35 region, while mutations in the upstream helix, which is thought to contact the phosphate backbone, have sequence-independent effects on promoter recognition.