The Docking Stage of Yeast Vacuole Fusion Requires the Transfer of Proteins from a Cis-Snare Complex to a Rab/Ypt Protein

Price, Albert; Seals, Darren F.; Wickner, William; Ungermann, Christian

doi:10.1083/jcb.148.6.1231

Cited by 194 publications

(222 citation statements)

References 45 publications

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“…Within this complex, both the SM protein Vps33p and the Rab-family small GTPase Ypt7p were found in association with the SNARE machinery (Wurmser et al, 2000;Price et al, 2000). Our results together with the previous results with the HOPS complex imply that in different membrane fusion events, there exists a molecular machinery that links the vesicle tethering machinery with the SNARE machinery, possibly through a small GTP binding protein.…”

Section: Discussionsupporting

confidence: 77%

Molecular Interactions Position Mso1p, a Novel PTB Domain Homologue, in the Interface of the Exocyst Complex and the Exocytic SNARE Machinery in Yeast

Knop

Miller

Mazza

et al. 2005

MBoC

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In this study, we have analyzed the association of the Sec1p interacting protein Mso1p with the membrane fusion machinery in yeast. We show that Mso1p is essential for vesicle fusion during prospore membrane formation. Green fluorescent protein-tagged Mso1p localizes to the sites of exocytosis and at the site of prospore membrane formation. In vivo and in vitro experiments identified a short amino-terminal sequence in Mso1p that mediates its interaction with Sec1p and is needed for vesicle fusion. A point mutation, T47A, within the Sec1p-binding domain abolishes Mso1p functionality in vivo, and mso1T47A mutant cells display specific genetic interactions with sec1 mutants. Mso1p coimmunoprecipitates with Sec1p, Sso1/2p, Snc1/2p, Sec9p, and the exocyst complex subunit Sec15p. In sec4-8 and SEC4I133 mutant cells, association of Mso1p with Sso1/2p, Snc1/2p, and Sec9p is affected, whereas interaction with Sec1p persists. Furthermore, in SEC4I133 cells the dominant negative Sec4I133p coimmunoprecipitates with Mso1p-Sec1p complex. Finally, we identify Mso1p as a homologue of the PTB binding domain of the mammalian Sec1p binding Mint proteins.These results position Mso1p in the interface of the exocyst complex, Sec4p, and the SNARE machinery, and reveal a novel layer of molecular conservation in the exocytosis machinery. INTRODUCTIONEvolutionarily conserved molecular machinery regulates transport vesicle targeting, tethering, and fusion in eukaryotic cells. In yeast Saccharomyces cerevisiae this machinery involves the activity of the eight-subunit (Sec3p, Sec5p, Sec6p, Sec8p, Sec10p, Sec15p, Exo70p, and Exo84p) tethering complex, the exocyst, a rab family small GTPase Sec4p, and the exocytic SNARE complex (Snc1/2p, Sec9p, and Sso1/2p) thought to drive the actual lipid bilayer fusion . The exocyst subunit Sec15p has been shown to act as an effector for Sec4p (Guo et al., 1999). In addition, sec4-8 mutant cells are defective in Snc1/2p-Sec9p-Sso1/2p SNARE complex assembly (Carr et al., 1999). Despite these and numerous other studies, the regulatory mechanisms for SNARE complex formation are still poorly understood. The Sec1/Munc18 (SM) protein family members represent central regulators of SNARE complex function. These proteins perform an essential, albeit currently poorly understood function in SNARE complex regulation (Gallwitz and Jahn, 2003;Toonen and Verhage, 2003;Kauppi et al., 2004).Yeast S. cerevisiae possesses four Sec1p-family proteins: Sec1p mediates vesicle fusion at the plasma membrane (Novick et al., 1981;Carr et al., 1999), Sly1p mediates vesicle fusion at the endoplasmic reticulum-Golgi interface (Ossig et al., 1991), Vps33p is required for endosome to vacuole transport and vacuole maintenance (Banta et al., 1990), and Vps45p mediates Golgi-to-vacuole transport (Piper et al., 1994;Cowles et al., 1994). Sec1p is the closest homologue of the mammalian Munc18-1 that has been shown to associate with syntaxin 1 and to regulate the syntaxin 1-synaptobrevin-SNAP-25 SNARE complex assembly (Misura et al., 2000;Kaup...

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Section: Discussionsupporting

confidence: 77%

Molecular Interactions Position Mso1p, a Novel PTB Domain Homologue, in the Interface of the Exocyst Complex and the Exocytic SNARE Machinery in Yeast

Knop

Miller

Mazza

et al. 2005

MBoC

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“…Both Ypt7p and Vam3p have been shown to play important roles in many known trafficking pathways leading to the vacuole (53)(54)(55)(56)(57)(58)(59)(60). These include the sorting of carboxy peptidase Y to the vacuole (53), the targeting of autophagosomes to the vacuole, the cytosol to vacuole targeting pathway (54 -56), and homotypic vacuole fusion (57)(58)(59)(60). In addition, for the vacuoledependent FBPase degradation pathway, the last step requires the participation of Ypt7p and Vam3p (36).…”

Section: Distinct Proteolytic Pathways For Gluconeogenic Enzymesmentioning

confidence: 99%

Degradation of the Gluconeogenic Enzymes Fructose-1,6-bisphosphatase and Malate Dehydrogenase Is Mediated by Distinct Proteolytic Pathways and Signaling Events

Hung

Brown

Wolfe

et al. 2004

Journal of Biological Chemistry

109

143

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The key gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase) is subjected to catabolite inactivation and degradation when glucose-starved cells are replenished with fresh glucose. In various studies, the proteasome and the vacuole have each been reported to be the major site of FBPase degradation. Because different growth conditions were used in these studies, we examined whether variations in growth conditions could alter the site of FBPase degradation. Here, we demonstrated that FBPase was degraded outside the vacuole (most likely in the proteasome), when glucose was added to cells that were grown in low glucose media for a short period of time. By contrast, cells that were grown in the same low glucose media for longer periods of time degraded FBPase in the vacuole in response to glucose. Another gluconeogenic enzyme malate dehydrogenase (MDH2) showed the same degradation characteristics as FBPase in that the short term starvation of cells led to a non-vacuolar degradation, whereas long term starvation resulted in the vacuolar degradation of this protein.The N-terminal proline is required for the degradation of FBPase and MDH2 for both the vacuolar and nonvacuolar proteolytic pathways. The cAMP signaling pathway and the phosphorylation of glucose were needed for the vacuolar-dependent degradation of FBPase and MDH2. By contrast, the cAMP-dependent signaling pathway was not involved in the non-vacuolar degradation of these proteins, although the phosphorylation of glucose was required.

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“…identify molecules involved in the trafficking of Vid vesicle to the vacuole, we used an alkaline phosphatase assay that was originally developed by the Wickner laboratory to study homotypic vacuole-vacuole fusion (42,(47)(48)(49)(50)(51)(52) and modified by the Ohsumi laboratory to study the starvation-induced autophagy pathway (12)(13)(14)(15)(16). These assays take advantage of two key characteristics of alkaline phosphatase.…”

Section: A Fusion Protein For the Study Of Vid Vesicle Trafficking-tomentioning

confidence: 99%

The Vid Vesicle to Vacuole Trafficking Event Requires Components of the SNARE Membrane Fusion Machinery

Brown

Liu

Hung

et al. 2003

Journal of Biological Chemistry

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Lysosomal protein degradation is induced when cultured cells are starved of nutrients or serum. This process recycles amino acids and allows for the synthesis of proteins that are crucial for cell survival during starvation. Several mechanisms are responsible for increased lysosomal degradation during starvation (1-5). The macroautophagy pathway utilizes autophagosomes to deliver cytosolic proteins and organelles to lysosomes for degradation. The chaperone-mediated autophagy pathway targets cytosolic proteins containing a KFERQ motif for degradation. These proteins are recognized by the heat shock protein hsc73 and a lysosomal receptor LGP96 (1, 6 -9).

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The Docking Stage of Yeast Vacuole Fusion Requires the Transfer of Proteins from a Cis-Snare Complex to a Rab/Ypt Protein

Cited by 194 publications

References 45 publications

Molecular Interactions Position Mso1p, a Novel PTB Domain Homologue, in the Interface of the Exocyst Complex and the Exocytic SNARE Machinery in Yeast

Molecular Interactions Position Mso1p, a Novel PTB Domain Homologue, in the Interface of the Exocyst Complex and the Exocytic SNARE Machinery in Yeast

Degradation of the Gluconeogenic Enzymes Fructose-1,6-bisphosphatase and Malate Dehydrogenase Is Mediated by Distinct Proteolytic Pathways and Signaling Events

The Vid Vesicle to Vacuole Trafficking Event Requires Components of the SNARE Membrane Fusion Machinery

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