The H-abc Domain of the SNARE Vam3 Interacts with the HOPS Tethering Complex to Facilitate Vacuole Fusion
Autor(en): | Luerick, Anna Kuhlee, Anne Broecker, Cornelia Kuemmel, Daniel Raunser, Stefan Ungermann, Christian |
Stichwörter: | Biochemistry & Molecular Biology; DOCKING; ENDOSOME; MEMBRANE; N-TERMINAL PEPTIDE; PHOSPHOINOSITIDES; PROTEIN VPS33; RAB INTERACTIONS; RECRUITMENT; STRUCTURAL BASIS; YEAST VACUOLE | Erscheinungsdatum: | 2015 | Herausgeber: | ELSEVIER | Journal: | JOURNAL OF BIOLOGICAL CHEMISTRY | Volumen: | 290 | Ausgabe: | 9 | Startseite: | 5405 | Seitenende: | 5413 | Zusammenfassung: | Membrane fusion at vacuoles requires a consecutive action of the HOPS tethering complex, which is recruited by the Rab GTPase Ypt7, and vacuolar SNAREs to drive membrane fusion. It is assumed that the Sec1/Munc18-like Vps33 within the HOPS complex is largely responsible for SNARE chaperoning. Here, we present direct evidence for HOPS binding to SNAREs and the H-abc domain of the Vam3 SNARE protein, which may explain its function during fusion. We show that HOPS interacts strongly with the Vam3 H-abc domain, assembled Q-SNAREs, and the R-SNARE Ykt6, but not the Q-SNARE Vti1 or the Vam3 SNARE domain. Electron microscopy combined with Nanogold labeling reveals that the binding sites for vacuolar SNAREs and the H-abc domain are located in the large head of the HOPS complex, where Vps16 and Vps33 have been identified before. Competition experiments suggest that HOPS bound to the H-abc domain can still interact with assembled Q-SNAREs, whereas Q-SNARE binding prevents recognition of the H-abc domain. In agreement, membranes carrying Vam(3)Delta H-abc fuse poorly unless an excess of HOPS is provided. These data suggest that the H-abc domain of Vam3 facilitates the assembly of the HOPS/SNARE machinery at fusion sites and thus supports efficient membrane fusion. |
DOI: | 10.1074/jbc.M114.631465 |
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geprüft am 13.05.2024