Structure and Function of Membrane-Remodeling ESCRT-III Assemblies

Abstract

The ESCRT pathway mediates a series of important cellular membrane remodeling and fission events, including cytokinetic abscission. During these processes, ESCRT-III family proteins, including CHMP1B and IST1, form filaments that appear to constrict membranes and facilitate fission. Here, we report the first structure of “open” and assembled ESCRT-III proteins. Near-atomic resolution electron cryomicroscopy reveals that filaments comprise a copolymeric assembly of an open conformation inner strand and, unexpectedly, a closed conformation outer strand.