SWI/SNF相关转录预起始复合物的结构基础
SWI/SNF相关转录预起始复合物的结构基础
作者： 小柯机器人 发布时间：2026/9/12 10:17:23
本期文章：《细胞》：Online/在线发表
2026年，美国斯坦福大学Shigeki Nagai等科学家在《细胞》（Cell）发表研究，解析了SWI/SNF相关转录预起始复合物的高分辨率结构。
交配型转换/蔗糖非发酵（SWI/SNF）染色质重塑复合物在启动子上移除和重新定位核小体，以启动转录。尽管长期以来被认为独立发挥作用，研究人员发现SWI/SNF是转录机器的组成部分。SWI/SNF与RNA聚合酶II预起始复合物（PIC）、Mediator和核小体结合，整个组装体二聚化形成巨大的7兆道尔顿复合物。研究人员展示了PIC-Mediator-SWI/SNF和PIC-Mediator-SWI/SNF-核小体复合物的高分辨率冷冻电镜结构，以及交联和质谱分析结果。这些结构揭示了SWI/SNF如何通过稳定PIC组织和协同重塑所谓的+1核小体来增强转录起始。结构模型提示两种DNA转位酶——SWI/SNF的Snf2和TFIIH的Ssl2——协同作用以启动转录。
附：英文原文
Title: Structural basis of a SWI/SNF-associated transcription pre-initiation complex
Author: Shigeki Nagai, Chun Yang, Dong-Hua Chen, Michael J. Trnka, David A. Bushnell, Alma L. Burlingame, Kenji Murakami, Roger D. Kornberg
Issue&Volume:
Abstract: The mating type switching/sucrose non-fermenting (SWI/SNF) chromatin remodeling complex removes and repositions nucleosomes at promoters for the initiation of transcription. Though long thought to function independently, we find that SWI/SNF is an integral component of the transcription machinery. SWI/SNF associates with an RNA polymerase II pre-initiation complex (PIC), Mediator, and a nucleosome, and the entire assembly dimerizes to form a giant 7-megadalton complex. We present high-resolution cryo-electron microscopy (cryo-EM) structures of both PIC-Mediator-SWI/SNF and PIC-Mediator-SWI/SNF-nucleosome complexes, together with results of cross-linking and mass spectrometry. The structures reveal how SWI/SNF enhances the initiation of transcription through stabilization of PIC organization and concerted remodeling of the so-called +1 nucleosome. The structural model suggests the coordinated actions of two DNA translocases, Snf2 of SWI/SNF and Ssl2 of TFIIH, for the initiation of transcription.
DOI: 10.1016/j.cell.2026.08.020
Source: https://www.cell.com/cell/abstract/S0092-8674(26)00947-5