Biophysical Society Thematic Meeting| Padova 2019

Quantitative Aspects of Membrane Fusion and Fission

Poster Abstracts

39-POS Board 39 DIRECT OBSERVATION OF DYNAMIN-INDUCED MEMBRANE FISSION BY HIGH- SPEED ATOMIC FORCE MICROSCOPY Yuliang Zhang 1 ; Javier Vera Lillo 3 ; Vadim Frolov 3,4 ; Aleksandr Noy 1,2 ; 1 Lawrence Livermore National Laboratory, Biology and Biotechnology Division, Livermore, California, USA 2 University of California Merced, School of Natural Sciences, Merced, California, USA 3 University of the Basque Country, Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, Leioa, Vizcaya, Spain 4 Basque Foundation for Science, Ikerbasque, Bilbao, Vizcaya, Spain Dynamin1 is a large GTPase mediating membrane fission step during endocytosis. The ability of Dynamin1 to self-assemble into a helix engulfing the neck of the endocytic vesicle is critical for its function. Even though the structure of dynamin1 in the assembled state on the membrane has been reported recently, how the cooperative GTP hydrolysis by Dyn1min1 polymer leads to fission remains a subject of considerable controversy. We have used high-speed atomic force microscopy to investigate real-time dynamics of GTP-dependent rearrangements of dynamin1 self-assembled on lipid nanotubes. The movies show GTP-induced local conformational rearrangements of the polymer leading to rapid membrane fission. Our observations are consistent with the hypothesis that fission is stochastically coupled to GTP-driven dynamics of short dynamin scaffolds that induce acute and transient curvature stress.

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