Nanoscale dynamics of Dynamin 1 helices reveals squeeze-twist deformation mode critical for membrane fission

• 成果类型: Article
• 署名作者: Zhang, Yuliang; Lillo, Javier Vera; Abdelrasoul, Mahmoud Shaaban Mohamed; Wang, Yaqing; Arrasate, Pedro; Frolov, Vadim A.; Noy, Aleksandr
• 署名单位: United States Department of Energy (DOE); Lawrence Livermore National Laboratory; Consejo Superior de Investigaciones Cientificas (CSIC); University of Basque Country; CSIC - UPV EHU - Instituto Biofisika; University of Basque Country; Basque Foundation for Science; University of California System; University of California Merced; Barcelona Institute of Science & Technology; Universitat Politecnica de Catalunya; Institut de Ciencies Fotoniques (ICFO); Egyptian Knowledge Bank (EKB); Assiut University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14843
• DOI: 10.1073/pnas.2321514121
• 发表日期: 2024-12-03
• 关键词: real-time analysis

摘要

Dynamin 1 (Dyn1) GTPase, a principal driver of membrane fission during synaptic endocytosis, self-assembles into short mechanoactive helices cleaving the necks of endocytic vesicles. While structural information about Dyn1 helix is abundant, little is known about the nanoscale dynamics of the helical scaffolding at the moment of fission, complicating mechanistic understanding of Dyn1 action. To address the role of the helix dynamics in fission, we used High-Speed Atomic Force Microscopy (HS-AFM) and fluorescence microscopy to track and compare the spatiotemporal characteristics of the helices formed by wild-type Dyn1 and its K44A mutant impaired in GTP hydrolysis on minimal lipid membrane templates. In the absence of nucleotide, membrane- bound WT Dyn1 and K44A Dyn1 self-assembled into tubular protein scaffolding of similar diameter encaging the lipid bilayer. In both cases, the GTP addition caused scaffold constriction coupled with formation of 20 to 30 nm nanogaps in the protein coverage. While both proteins reached scaffold diameters characteristic for membrane superconstriction causing fission, the fission was detected only with WT Dyn1. We associated the fission activity with the dynamic evolution of the nanogaps: K44A Dyn1 gaps were static, while WT Dyn1 gaps actively evolved via repetitive nonaxisymmetric constriction-bending deformations caused by localized GTP hydrolysis. Modeling of the deformations implicated filament twist as an additional deformation mode which combines with superconstriction to facilitate membrane fission. Our results thus show that the dynamics of the Dyn1 helical scaffold goes beyond radial constriction and involves nonaxisymmetric deformations, where filament twist emerges as a critical driver of membrane fission.