Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802;
Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA 16802.
Proc Natl Acad Sci U S A. 2017 Aug 1;114(31):8211-8216. doi: 10.1073/pnas.1702741114. Epub 2017 Jun 26.
Reiterative transcription is a noncanonical form of RNA synthesis in which a nucleotide specified by a single base in the DNA template is repetitively added to the nascent transcript. Here we determined the crystal structure of an RNA polymerase, the bacterial enzyme from , engaged in reiterative transcription during transcription initiation at a promoter resembling the promoter of The structure reveals that the reiterative transcript detours from the dedicated RNA exit channel and extends toward the main channel of the enzyme, thereby allowing RNA extension without displacement of the promoter recognition σ-factor. Nascent transcripts containing reiteratively added G residues are eventually extended by nonreiterative transcription, revealing an atypical pathway for the formation of a transcription elongation complex.
重复转录是一种非典型的 RNA 合成形式，其中 DNA 模板中单个碱基指定的核苷酸被反复添加到新生的转录本中。在这里，我们确定了一种 RNA 聚合酶的晶体结构，该酶来自 ，在类似于 的启动子处进行转录起始时参与重复转录。结构显示，重复转录本绕过专用 RNA 出口通道并延伸到酶的主通道，从而允许 RNA 延伸而不置换启动子识别 σ 因子。含有重复添加的 G 残基的新生转录本最终通过非重复转录延伸，揭示了转录延伸复合物形成的一种非典型途径。
