Molecular architecture of the multisubunit homotypic fusion and vacuole protein sorting (HOPS) tethering complex

Bröcker C, Kuhlee A, Gatsogiannis C, Balderhaar HJk, Hönscher C, Engelbrecht-Vandré S, Ungermann C, Raunser S

Zusammenfassung

Membrane fusion within the eukaryotic endomembrane system depends on the initial recognition of Rab GTPase on transport vesicles by multisubunit tethering complexes and subsequent coupling to SNARE-mediated fusion. The conserved vacuolar/lysosomal homotypic fusion and vacuole protein sorting (HOPS) tethering complex combines both activities. Here we present the overall structure of the fusion-active HOPS complex. Our data reveal a flexible $\approx$30-nm elongated seahorse-like structure, which can adopt contracted and elongated shapes. Surprisingly, both ends of the HOPS complex contain a Rab-binding subunit: Vps41 and Vps39. The large head contains in addition to Vps41 the SNARE-interacting Vps33, whereas Vps39 is found in the bulky tip of its tail. Vps11 and Vps18 connect head and tail. Our data suggest that HOPS bridges Ypt7-positive membranes and chaperones SNAREs at fusion sites.