The CORVET complex promotes tethering and fusion of Rab5/Vps21-positive membranes
Autor(en): | Balderhaar, Henning J. Kleine Lachmann, Jens Yavavli, Erdal Broecker, Cornelia Luerick, Anna Ungermann, Christian |
Stichwörter: | BIOGENESIS; endolysosomal system; LATE ENDOSOMES; Multidisciplinary Sciences; NUCLEOTIDE EXCHANGE; PROTEIN VPS33; RAB GTPASE; Science & Technology - Other Topics; SNARE COMPLEX; VACUOLE FUSION; VPS21; YEAST; YPT7 | Erscheinungsdatum: | 2013 | Herausgeber: | NATL ACAD SCIENCES | Enthalten in: | PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA | Band: | 110 | Ausgabe: | 10 | Startseite: | 3823 | Seitenende: | 3828 | Zusammenfassung: | Membrane fusion along the endocytic pathway occurs in a sequence of tethering, docking, and fusion. At endosomes and vacuoles, the CORVET (class C core vacuole/endosome tethering) and HOPS (homotypic fusion and vacuole protein sorting) tethering complexes require their organelle-specific Rabs for localization and function. Until now, despite the absence of experimental evidence, it has been assumed that CORVET is a membrane-tethering factor. To test this theory and understand the mechanistic analogies with the HOPS complex, we set up an in vitro system, and establish CORVET as a bona-fide tether for Vps21-positive endosome/vacuole membranes. Purified CORVET binds to SNAREs and Rab5/Vps21-GTP. We then demonstrate that purified CORVET can specifically tether Vps21-positive membranes. Tethering via CORVET is dose-dependent, stimulated by the GEF Vps9, and inhibited by Msb3, the Vps21-GAP. Moreover, CORVET supports fusion of isolated membranes containing Vps21. In agreement with its role as a tether, overexpressed CORVET drives Vps21, but not the HOPS-specific Ypt7 into contact sites between vacuoles, which likely represent vacuole-associated endosomes. We therefore conclude that CORVET is a tethering complex that promotes fusion of Rab5-positive membranes and thus facilitates receptor down-regulation and recycling at the late endosome. |
ISSN: | 00278424 | DOI: | 10.1073/pnas.1221785110 |
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geprüft am 08.06.2024