Structural Identification of the Vps18 β-Propeller Reveals a Critical Role in the HOPS Complex Stability and Function

• Published in: The Journal of biological chemistry 2014-11, Vol.289 (48), p.33503-33512
• Main Authors: Behrmann, Heide, Lürick, Anna, Kuhlee, Anne, Balderhaar, Henning Kleine, Bröcker, Cornelia, Kümmel, Daniel, Engelbrecht-Vandré, Siegfried, Gohlke, Ulrich, Raunser, Stefan, Heinemann, Udo, Ungermann, Christian
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Vesicular Transport - chemistry; Adaptor Proteins, Vesicular Transport - genetics; Adaptor Proteins, Vesicular Transport - metabolism; COP-Coated Vesicles - chemistry; COP-Coated Vesicles - genetics; COP-Coated Vesicles - metabolism; Crystal Structure; Endosome; HOPS; Membrane Biology; Membrane Fusion; Multiprotein Complexes - chemistry; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; Protein Stability; Protein Structure, Secondary; Protein Structure, Tertiary; Rab; Saccharomyces cerevisiae - chemistry; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; SNARE Proteins; Tethering Complex; Vacuole
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.602714

Membrane fusion at the vacuole, the lysosome equivalent in yeast, requires the HOPS tethering complex, which is recruited by the Rab7 GTPase Ypt7. HOPS provides a template for the assembly of SNAREs and thus likely confers fusion at a distinct position on vacuoles. Five of the six subunits in HOPS have a similar domain prediction with strong similarity to COPII subunits and nuclear porins. Here, we show that Vps18 indeed has a seven-bladed β-propeller as its N-terminal domain by revealing its structure at 2.14 Å. The Vps18 N-terminal domain can interact with the N-terminal part of Vps11 and also binds to lipids. Although deletion of the Vps18 N-terminal domain does not preclude HOPS assembly, as revealed by negative stain electron microscopy, the complex is instable and cannot support membrane fusion in vitro. We thus conclude that the β-propeller of Vps18 is required for HOPS stability and function and that it can serve as a starting point for further structural analyses of the HOPS tethering complex. Background: The HOPS tethering complex has five subunits with similar domain arrangements, but structural insights into these is scarce. Results: The N-terminal domain of Vps18 reveals the structure of a β-propeller. Conclusion: The β-propeller is dispensable for HOPS assembly but critical for stability and function. Significance: Our data provide evidence of an evolutionarily conserved domain within HOPS.