Luan Bai, Huang Xiuliang, Wu Jianping, Mei Ziqing, Wang Yiwei, Xue Xiaobin, Yan Chuangye, Wang Jiawei, Finley Daniel J, Shi Yigong, Wang Feng
Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China;
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 10081, China;
Proc Natl Acad Sci U S A. 2016 Mar 8;113(10):2642-7. doi: 10.1073/pnas.1601561113. Epub 2016 Feb 29.
The eukaryotic proteasome mediates degradation of polyubiquitinated proteins. Here we report the single-particle cryoelectron microscopy (cryo-EM) structures of the endogenous 26S proteasome from Saccharomyces cerevisiae at 4.6- to 6.3-Å resolution. The fine features of the cryo-EM maps allow modeling of 18 subunits in the regulatory particle and 28 in the core particle. The proteasome exhibits two distinct conformational states, designated M1 and M2, which correspond to those reported previously for the proteasome purified in the presence of ATP-γS and ATP, respectively. These conformations also correspond to those of the proteasome in the presence and absence of exogenous substrate. Structure-guided biochemical analysis reveals enhanced deubiquitylating enzyme activity of Rpn11 upon assembly of the lid. Our structures serve as a molecular basis for mechanistic understanding of proteasome function.
真核生物蛋白酶体介导多聚泛素化蛋白的降解。在此，我们报告了酿酒酵母内源性26S蛋白酶体在4.6至6.3埃分辨率下的单颗粒冷冻电子显微镜（cryo-EM）结构。冷冻电镜图谱的精细特征使得能够对调节颗粒中的18个亚基和核心颗粒中的28个亚基进行建模。蛋白酶体呈现出两种不同的构象状态，分别命名为M1和M2，它们分别对应于先前在ATP-γS和ATP存在下纯化的蛋白酶体的构象状态。这些构象也分别对应于存在和不存在外源底物时蛋白酶体的构象。基于结构的生化分析表明，盖子组装后Rpn11的去泛素化酶活性增强。我们的结构为蛋白酶体功能的机制理解提供了分子基础。
