A novel Sec18p/NSF-dependent complex required for Golgi-to-endosome transport in yeast.

Burd, Christopher G.; Peterson, Michael R.; Cowles, Christopher R.; Emr, Scott D.

doi:10.1091/mbc.8.6.1089

Cited by 148 publications

(174 citation statements)

References 95 publications

(110 reference statements)

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“…Vam3p was also found to be required for vacuolar inheritance, which results from homotypic fusion of newly formed vacuolar vesicles present in budding cells (Ungermann et al, 1999). Pep12p was identified as being required for transport to the prevacuole (Becherer et al, 1996;Burd et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Syntaxin 7 and VAMP-7 are SolubleN-Ethylmaleimide–sensitive Factor Attachment Protein Receptors Required for Late Endosome–Lysosome and Homotypic Lysosome Fusion in Alveolar Macrophages

Ward

Pevsner

Scullion

et al. 2000

MBoC

128

116

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Endocytosis in alveolar macrophages can be reversibly inhibited, permitting the isolation of endocytic vesicles at defined stages of maturation. Using an in vitro fusion assay, we determined that each isolated endosome population was capable of homotypic fusion. All vesicle populations were also capable of heterotypic fusion in a temporally specific manner; early endosomes, isolated 4 min after internalization, could fuse with endosomes isolated 8 min after internalization but not with 12-min endosomes or lysosomes. Lysosomes fuse with 12-min endosomes but not with earlier endosomes. Using homogenous populations of endosomes, we have identified Syntaxin 7 as a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) required for late endosome–lysosome and homotypic lysosome fusion in vitro. A bacterially expressed human Syntaxin 7 lacking the transmembrane domain inhibited homotypic late endosome and lysosome fusion as well as heterotypic late endosome–lysosome fusion. Affinity-purified antibodies directed against Syntaxin 7 also inhibited lysosome fusion in vitro but had no affect on homotypic early endosome fusion. Previous work suggested that human VAMP-7 (vesicle-associated membrane protein-7) was a SNARE required for late endosome–lysosome fusion. A bacterially expressed human VAMP-7 lacking the transmembrane domain inhibited both late endosome–lysosome fusion and homotypic lysosome fusion in vitro. These studies indicate that: 1) fusion along the endocytic pathway is a highly regulated process, and 2) two SNARE molecules, Syntaxin 7 and human VAMP-7, are involved in fusion of vesicles in the late endocytic pathway in alveolar macrophages.

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Section: Discussionmentioning

confidence: 99%

Syntaxin 7 and VAMP-7 are SolubleN-Ethylmaleimide–sensitive Factor Attachment Protein Receptors Required for Late Endosome–Lysosome and Homotypic Lysosome Fusion in Alveolar Macrophages

Ward

Pevsner

Scullion

et al. 2000

MBoC

128

116

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“…Yeast offers an exceptional opportunity to investigate this issue because its genome contains only seven t-SNAREs (Pelham, 2001a). Thus, our gradient fractions were also probed with antibodies recognizing the t-SNAREs of the late endosome (Pep12), cis-Golgi compartment (Sed5), vacuole (Vam3), and plasma membrane (Sso1 and Sso2) (Aalto et al, 1993;Banfield et al, 1994;Becherer et al, 1996;Burd et al, 1997;Nichols et al, 1997). None of these proteins displayed complete cofractionation with the PAS marker Atg9 ( Figure 2E).…”

Section: Molecular Biology Of the Cell 2192mentioning

confidence: 99%

Early Stages of the Secretory Pathway, but Not Endosomes, Are Required for Cvt Vesicle and Autophagosome Assembly inSaccharomyces cerevisiae

Reggiori

Wang

Nair

et al. 2004

MBoC

129

163

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The Cvt pathway is a biosynthetic transport route for a distinct subset of resident yeast vacuolar hydrolases, whereas macroautophagy is a nonspecific degradative mechanism that allows cell survival during starvation. Yet, these two vacuolar trafficking pathways share a number of identical molecular components and are morphologically very similar. For example, one of the hallmarks of both pathways is the formation of double-membrane cytosolic vesicles that sequester cargo before vacuolar delivery. The origin of the vesicle membrane has been controversial and various lines of evidence have implicated essentially all compartments of the endomembrane system. Despite the analogies between the Cvt pathway and autophagy, earlier work has suggested that the origin of the engulfing vesicle membranes is different; the endoplasmic reticulum is proposed to be required only for autophagy. In contrast, in this study we demonstrate that the endoplasmic reticulum and/or Golgi complex, but not endosomal compartments, play an important role for both yeast transport routes. Along these lines, we demonstrate that Berkeley bodies, a structure generated from the Golgi complex in sec7 cells, are immunolabeled with Atg8, a structural component of autophagosomes. Finally, we also show that none of the yeast t-SNAREs are located at the preautophagosomal structure, the presumed site of double-membrane vesicle formation. Based on our results, we propose two models for Cvt vesicle biogenesis. INTRODUCTIONThe lysosome/vacuole is the major cellular center for degradation, recycling, and storage of biological constituents. Several well-characterized transport routes are implicated in protein delivery to this organelle during normal growth conditions. These pathways are conserved among eukaryotic organisms, but work in the yeast Saccharomyces cerevisiae has had a major impact on their characterization and in the identification of the molecular machinery (Conibear and Stevens, 1998). The route called the alkaline phosphatase pathway provides a direct transport connection between the Golgi complex and the vacuole Piper et al., 1997). A second itinerary from the Golgi complex to the vacuole passes through the late endosome and is known as the carboxypeptidase Y pathway (Piper et al., 1995;Babst et al., 1998;Conibear and Stevens, 1998). These two pathways are required for the biogenesis and maintenance of vacuoles, whereas a third route, endocytosis, has a catabolic function. Endocytosis mediates the downregulation of plasma membrane proteins by delivering them via the late endosome to the vacuole for degradation (Hicke, 1999;Katzmann et al., 2002). Before reaching the late endosome, these proteins pass through the early endosome where some components are recycled back to the cell surface (Hicke et al., 1997;Prescianotto-Baschong and Riezman, 1998;Lewis et al., 2000). The carboxypeptidase Y pathway and endocytosis converge at the endosome where another route, the multivesicular body pathway, delivers both resident enzymes and substrates to the vac...

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“…This prediction has been borne out by more recent studies: many of the class D VPS genes encode components of a docking/fusion complex that is implicated in the fusion of late-Golgi-derived vesicles with the PVC. These include Vac1p, the yeast homologue of EEA1, which binds the Rab5 homologue Vps21p as well as the Sec1-like Vps45p and the endosomal t-SNARE Pep12p (Burd et al, 1997;Peterson et al, 1999;Tall et al, 1999). Class C Vps proteins include Vps11p, Vps18p, Vps16p, and the Sec1-like Vps33p, which form a complex that, together with the vacuolar t-SNARE Vam3p, the SNAP-25-like Vam7p, and the Rab protein Ypt7p, is required for the fusion of multiple transport intermediates with the vacuole (Haas et al, 1995;Darsow et al, 1997;Rieder and Emr, 1997;Sato et al, 1998;Ungermann and Wickner, 1998).…”

Section: Introductionmentioning

confidence: 99%

Vps52p, Vps53p, and Vps54p Form a Novel Multisubunit Complex Required for Protein Sorting at the Yeast Late Golgi

Conibear

Stevens

2000

MBoC

267

336

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The late Golgi of the yeast Saccharomyces cerevisiae receives membrane traffic from the secretory pathway as well as retrograde traffic from post-Golgi compartments, but the machinery that regulates these vesicle-docking and fusion events has not been characterized. We have identified three components of a novel protein complex that is required for protein sorting at the yeast late Golgi compartment. Mutation of VPS52, VPS53, or VPS54 results in the missorting of 70% of the vacuolar hydrolase carboxypeptidase Y as well as the mislocalization of late Golgi membrane proteins to the vacuole, whereas protein traffic through the early part of the Golgi complex is unaffected. A vps52/53/54 triple mutant strain is phenotypically indistinguishable from each of the single mutants, consistent with the model that all three are required for a common step in membrane transport. Native coimmunoprecipitation experiments indicate that Vps52p, Vps53p, and Vps54p are associated in a 1:1:1 complex that sediments as a single peak on sucrose velocity gradients. This complex, which exists both in a soluble pool and as a peripheral component of a membrane fraction, colocalizes with markers of the yeast late Golgi by immunofluorescence microscopy. Together, the phenotypic and biochemical data suggest that VPS52, VPS53, and VPS54 are required for the retrograde transport of Golgi membrane proteins from an endosomal/ prevacuolar compartment. The Vps52/53/54 complex joins a growing list of distinct multisubunit complexes that regulate membrane-trafficking events.

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A novel Sec18p/NSF-dependent complex required for Golgi-to-endosome transport in yeast.

Cited by 148 publications

References 95 publications

Syntaxin 7 and VAMP-7 are SolubleN-Ethylmaleimide–sensitive Factor Attachment Protein Receptors Required for Late Endosome–Lysosome and Homotypic Lysosome Fusion in Alveolar Macrophages

Syntaxin 7 and VAMP-7 are SolubleN-Ethylmaleimide–sensitive Factor Attachment Protein Receptors Required for Late Endosome–Lysosome and Homotypic Lysosome Fusion in Alveolar Macrophages

Early Stages of the Secretory Pathway, but Not Endosomes, Are Required for Cvt Vesicle and Autophagosome Assembly inSaccharomyces cerevisiae

Vps52p, Vps53p, and Vps54p Form a Novel Multisubunit Complex Required for Protein Sorting at the Yeast Late Golgi

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