Biophysical Society Conference | Tahoe 2022

Molecular Biophysics of Membranes

Thursday Speaker Abstracts

DISSECTING MEMBRANE STRUCTURE AND REMODELING USING CRYO- ELECTRON TOMOGRAPHY Kelly K. Lee ; 1 University of Washington, Seattle, WA, USA Membranes are lipidic structures that define biological compartments in cells, organelles, and enveloped viruses. Because membranes serve such fundamental roles, essential protein machinery has evolved whose function is to manipulate membrane bilayers and remodel them during key biological processes. Until recently, it has been challenging to image membrane structure with resolution of leaflets, local curvature, and non-bilayer organizations, and it has been even more challenging to capture the protein machinery in the functional intermediate states that drive membrane remodeling. Cryo-electron microscopy provides a means to flash freeze liposomes, vesicles, and proteoliposomes, capturing the biological systems with native hydration and structures intact. From axial angular tilt images of the specimens, it is possible to reconstruct three-dimensional tomograms that provide sub-nanometer resolution of the membranes and associated proteins. With this approach, one can trigger a reaction and then capture and reconstruct 3-dimensional images of the reaction at intermediate stages. By preparing cryo-EM specimens over a time course, we capture snapshots across the population of reaction intermediates, allowing us to trace the reaction pathways for protein-mediated membrane remodeling. Our investigations of lipid microdomains and protein-mediated membrane fusion by enveloped viruses highlight the versatility of cryo-ET in capturing the fine structure of membranes and their interplay with membrane-remodeling protein machinery. From this, we gain new structural and mechanistic insights into complex biological processes.

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