Vps60 initiates formation of alternative membrane-bound ESCRT-III filaments
Endosomal sorting complex required for transport-III (ESCRT-III)-driven membrane remodeling participates in many crucial cellular functions, from cell division to endosome maturation, and occurs on essentially all cellular organelles. In eukaryotes, ESCRT-III displays a remarkable molecular diversity in its subunits which may have been acquired through evolution to perform novel cellular functions. Here, we describe and characterize a novel ESCRT-III polymer initiated by the subunit Vps60. Membrane-bound Vps60 polymers recruit ESCRT-III subunits Vps2, Vps24, Did2 and Ist1, and undergo polymer turnover powered by the ATPase Vps4. Snf7- and Vps60 filaments can coexist on membranes without interacting. Their nucleation, polymerization and recruitment of downstream subunits remains unaffected by the presence of the respective other polymer. Taken together, our results suggest Vps60 and Snf7 form distinct ESCRT-III polymers, which overall, supports the notion of evolutionary diversification of ESCRT-III assemblies to perform specific cellular functions.