Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK.
Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
J Mol Biol. 2019 Sep 20;431(20):3960-3974. doi: 10.1016/j.jmb.2019.04.022. Epub 2019 Apr 25.
Cellular RNA polymerase is a multi-subunit macromolecular assembly responsible for gene transcription, a highly regulated process conserved from bacteria to humans. In bacteria, sigma factors are employed to mediate gene-specific expression in response to a variety of environmental conditions. The major variant σ factor, σ, has a specific role in stress responses. Unlike σ-dependent transcription, which often can spontaneously proceed to initiation, σ-dependent transcription requires an additional ATPase protein for activation. As a result, structures of a number of distinct functional states during the dynamic process of transcription initiation have been captured using the σ system with both x-ray crystallography and cryo electron microscopy, furthering our understanding of σ-dependent transcription initiation and DNA opening. Comparisons with σ and eukaryotic polymerases reveal unique and common features during transcription initiation.
细胞 RNA 聚合酶是一种多亚基的大分子组装体，负责基因转录，这是一个从细菌到人类都保守的高度调控过程。在细菌中，σ 因子被用来介导基因特异性表达，以响应各种环境条件。主要的变体 σ 因子 σ 在应激反应中具有特定的作用。与 σ 依赖性转录不同，后者通常可以自发地进行起始，而 σ 依赖性转录需要额外的 ATP 酶蛋白来激活。因此，使用带有 x 射线晶体学和 cryo 电子显微镜的 σ 系统，捕获了转录起始的动态过程中的许多不同功能状态的结构，进一步加深了我们对 σ 依赖性转录起始和 DNA 打开的理解。与 σ 和真核聚合酶的比较揭示了转录起始过程中的独特和共同特征。
