Three- dimensional architecture of ESCRT- III flat spirals on the membrane

• 成果类型: Article
• 署名作者: Liu, Mingdong; Liu, Yunhui; Song, Tiefeng; Yang, Liuyan; Qi, Lei; Zhang, Yu- Zhong; Wang, Yong; Abcd, Qing- Tao Shen
• 署名单位: Southern University of Science & Technology; Southern University of Science & Technology; ShanghaiTech University; ShanghaiTech University; Zhejiang University; Shandong University; Shandong University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10263
• DOI: 10.1073/pnas.2319115121
• 发表日期: 2024-05-14
• 关键词: multivesicular body pathway; endosome-associated complex; structural basis; sorting complex; cryo-em; helical structures; protein; machinery; ubiquitin; scission

摘要

The endosomal sorting complexes required for transport (ESCRTs) are responsible for membrane remodeling in many cellular processes, such as multivesicular body biogenesis, viral budding, and cytokinetic abscission. ESCRT- III, the most abundant ESCRT subunit, assembles into flat spirals as the primed state, essential to initiate membrane invagination. However, the three- dimensional architecture of ESCRT- III flat spirals remained vague for decades due to highly curved filaments with a small diameter and a single preferred orientation on the membrane. Here, we unveiled that yeast Snf7, a component of ESCRT- III, forms flat spirals on the lipid monolayers using cryogenic electron microscopy. We developed a geometry- constrained Euler angle-assigned reconstruction strategy and obtained moderate- resolution structures of Snf7 flat spirals with varying curvatures. Our analyses showed that Snf7 subunits recline on the membrane with N- terminal motifs alpha 0 as anchors, adopt an open state with fused alpha 2/3 helices, and bend alpha 2/3 gradually from the outer to inner parts of flat spirals. In all, we provide the orientation and conformations of ESCRT- III flat spirals on the membrane and unveil the underlying assembly mechanism, which will serve as the initial step in understanding how ESCRTs drive membrane abscission.