Repression of the lambda pcin promoter by integrative host factor.
Repression of the lambda pcin promoter by integrative host factor.
复制标题
整合宿主因子抑制 lambda pcin 启动子。
DOI：
10.1016/0022-2836(89)90169-1
复制
发表时间：
1989
影响因子：
5.6
通讯作者：
Gottesman,ME
中科院分区：
文献类型：
--
作者：
Griffo,G;Oppenheim,AB;Gottesman,ME
Thecin-1突变在λ噬菌体的tR 1区域产生了一个新的启动子（pcin）。pcin启动子组成型转录I阻遏物基因。λcin-1不能在缺乏整合宿主因子（IHF）的大肠杆菌中增殖。λcI−cin-1在IHF−突变体中正常生长，表明来自pcin的阻遏物过量产生阻断了裂解生长。IHF结合位点与pcin启动子重叠的存在使我们假设IHF作为pcin转录的阻遏物起作用。我们发现pcin启动子在缺乏IHF的宿主中比在野生型细胞中的活性高5倍，体外研究表明IHF直接抑制pcin的转录起始。流产启动和凝胶阻滞试验表明，IHF干扰RNA聚合酶的结合pcin启动子。结合在开放启动子复合物中的RNA聚合酶对IHF具有抗性。我们建议，IHF结合到pcin启动子区阻断RNA聚合酶的启动子的结合，无论是通过覆盖特定的核苷酸或通过扭曲DNA结构。
Thecin-1 mutation creates a new promoter (pcin) in the tR1 region of bacteriophage lambda. The pcin promoter transcribes thecIrepressor gene constitutively. λcin-1 does not propagate onEscherichia colimutants lacking the integrative host factor (IHF). λcI−cin-1 grows normally in IHF−mutants, indicating that repressor overproduction from pcin blocks lytic growth. The presence of an IHF binding site which overlaps the pcin promoter led us to the hypothesis that IHF functions as a repressor of pcin transcription. We find that the pcin promoter is fivefold more active in a host lacking IHF than in wild-type cells.In vitrostudies show that IHF directly inhibits transcription initiation at pcin. Abortive initiation and gel retardation assays demonstrate that IHF interferes with the binding of RNA polymerase to the pcin promoter. RNA polymerase bound in an open promoter complex is resistant to IHF. We propose that IHF binding to the pcin promoter region blocks the binding of RNA polymerase to the promoter, either by covering specific nucleotides or by distorting DNA structure.