Kohler R, Mooney R A, Mills D J, Landick R, Cramer P
Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany.
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
Science. 2017 Apr 14;356(6334):194-197. doi: 10.1126/science.aal3059.
DNA transcription is functionally coupled to messenger RNA (mRNA) translation in bacteria, but how this is achieved remains unclear. Here we show that RNA polymerase (RNAP) and the ribosome of can form a defined transcribing and translating "expressome" complex. The cryo-electron microscopic structure of the expressome reveals continuous protection of ~30 nucleotides of mRNA extending from the RNAP active center to the ribosome decoding center. The RNAP-ribosome interface includes the RNAP subunit α carboxyl-terminal domain, which is required for RNAP-ribosome interaction in vitro and for pronounced cell growth defects upon translation inhibition in vivo, consistent with its function in transcription-translation coupling. The expressome structure can only form during transcription elongation and explains how translation can prevent transcriptional pausing, backtracking, and termination.
在细菌中，DNA转录与信使核糖核酸（mRNA）翻译在功能上相互偶联，但具体实现方式仍不清楚。在此，我们表明RNA聚合酶（RNAP）和核糖体能够形成一个特定的转录和翻译“表达体”复合物。表达体的冷冻电子显微镜结构揭示了从RNAP活性中心延伸至核糖体解码中心的约30个核苷酸的mRNA受到持续保护。RNAP - 核糖体界面包括RNAP亚基α羧基末端结构域，该结构域在体外是RNAP - 核糖体相互作用所必需的，并且在体内翻译抑制时会导致明显的细胞生长缺陷，这与其在转录 - 翻译偶联中的功能一致。表达体结构仅在转录延伸过程中形成，并解释了翻译如何防止转录暂停、回溯和终止。
