Ederth Josefine, Artsimovitch Irina, Isaksson Leif A, Landick Robert
Department of Microbiology, Stockholm University, S-10691 Stockholm, Sweden.
J Biol Chem. 2002 Oct 4;277(40):37456-63. doi: 10.1074/jbc.M207038200. Epub 2002 Jul 29.
Regulation of RNA polymerase during initiation, elongation, and termination of transcription is mediated in part by interactions with intrinsic regulatory signals encoded in the RNA and DNA that contact the enzyme. These interactions include contacts to an 8-9-bp RNA:DNA hybrid within the active-site cleft of the enzyme, contacts to the melted nontemplate DNA strand in the vicinity of the hybrid, contacts to exiting RNA upstream of the hybrid, and contacts to approximately 20 bp of duplex DNA downstream of the active site. Based on characterization of an amino acid substitution (G1161R) and a deletion (Delta1149-1190) in the jaw domain of the bacterial RNA polymerase largest subunit (beta'), we report here that contacts of the jaw domain to downstream DNA at the leading edge of the transcription complex contribute to regulation during all three phases of transcription. The results provide insight into the role of the jaw domain-downstream DNA contact in transcriptional initiation and pausing and suggest possible explanations for the previously reported isolation of the jaw mutants based on reduced ColEI plasmid replication.
在转录起始、延伸和终止过程中，RNA聚合酶的调控部分是通过与RNA和DNA中编码的内在调控信号相互作用来介导的，这些信号与酶接触。这些相互作用包括与酶活性位点裂隙内8 - 9个碱基对的RNA:DNA杂交体的接触、与杂交体附近解链的非模板DNA链的接触、与杂交体上游输出RNA的接触以及与活性位点下游约20个碱基对的双链DNA的接触。基于对细菌RNA聚合酶最大亚基（β'）颌结构域中一个氨基酸取代（G1161R）和一个缺失（Δ1149 - 1190）的表征，我们在此报告，转录复合物前沿的颌结构域与下游DNA的接触在转录的所有三个阶段都有助于调控。这些结果为颌结构域 - 下游DNA接触在转录起始和暂停中的作用提供了见解，并为先前报道的基于ColEI质粒复制减少而分离出颌突变体的现象提出了可能的解释。
