Sec18p (NSF)-Driven Release of Sec17p (α-SNAP) Can Precede Docking and Fusion of Yeast Vacuoles

Mayer, Andreas; Wickner, William; Haas, Albert

doi:10.1016/s0092-8674(00)81084-3

Cited by 565 publications

(671 citation statements)

References 60 publications

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“…Consistent with this possibility, syntaxin 3 (but not coexpressed syntaxin 2 or 4) has been localized to zymogen granules in pancreatic acinar cells (Gaisano et al, 1996), recycling tubulovesicles in gastric parietal cells (Bennett, manuscript in preparation) and secretory granules in eosinophils (Bennett, unpublished data). Recent data indicate that under certain circumstances, NSF acts solely on transport vesicles, prior to docking or fusion of these vesicles with their target (Mayer et al, 1996;Steel et al, 1996). This raises the possibility that v-SNAREs and t-SNAREs may interact on the same transport vesicle.…”

Section: Discussionmentioning

confidence: 99%

Differential localization of syntaxin isoforms in polarized Madin-Darby canine kidney cells.

Low

Chapin

Weimbs

et al. 1996

MBoC

225

223

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Syntaxins, integral membrane proteins that are part of the ubiquitous membrane fusion machinery, are thought to act as target membrane receptors during the process of vesicle docking and fusion. Several isoforms of the syntaxin family have been previously identified in mammalian cells, some of which are localized to the plasma membrane. We investigated the subcellular localization of these putative plasma membrane syntaxins in polarized epithelial cells, which are characterized by the presence of distinct apical and basolateral plasma membrane domains. Syntaxins 2, 3, and 4 were found to be endogenously present in Madin-Darby canine kidney cells. The localization of syntaxins 1A, 1B, 2, 3, and 4 in stably transfected Madin-Darby canine kidney cell lines was studied with confocal immunofluorescence microscopy. Each syntaxin isoform was found to have a unique pattern of localization. Syntaxins 1A and 1B were present only in intracellular structures, with little or no apparent plasma membrane staining. In contrast, syntaxin 2 was found on both the apical and basolateral surface, whereas the plasma membrane localization of syntaxins 3 and 4 were restricted to the apical or basolateral domains, respectively. Syntaxins are therefore the first known components of the plasma membrane fusion machinery that are differentially localized in polarized cells, suggesting that they may play a central role in targeting specificity.

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Section: Discussionmentioning

confidence: 99%

Differential localization of syntaxin isoforms in polarized Madin-Darby canine kidney cells.

Low

Chapin

Weimbs

et al. 1996

MBoC

225

223

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“…Samples were resuspended in 60 l of sample buffer (62.5 mM pH 6.8,10% [vol/vol] glycerol,2% [wt/vol] SDS, 140 mM ␤-mercaptoethanol) and analyzed by SDS-PAGE and immunoblotting. Sec17p release assays were performed as previously described (Mayer et al, 1996) except that 5 g/ml recombinant Sec18p was also added. Vacuole-bound actin was examined over the course of standard fusion reactions without the addition of cytosol to limit rebinding.…”

Section: Protein Processing and Analysismentioning

confidence: 99%

“…This analysis showed that the increase in fusion is primarily due to an increase in the rate at early time points ( Figure 10A, bottom panel). To initiate membrane fusion vacuoles undergo priming, a process requiring ATP hydrolysis by Sec18p and the release of Sec17p (Mayer et al, 1996). Because the difference in fusion rates were most dramatic at early time points, we examined if priming kinetics were altered because of ERG6 induction.…”

Section: Modification Of Vacuolar Lipids Via Erg6 Inductionmentioning

confidence: 99%

Enhanced Membrane Fusion in Sterol-enriched Vacuoles Bypasses the Vrp1p Requirement

Tedrick

Trischuk

Lehner

et al. 2004

MBoC

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Organization of lipids into membrane microdomains is a vital mechanism of protein processing. Here we show that overexpression of ERG6, a gene involved in ergosterol synthesis, elevates sterol levels 1.5-fold on the vacuole membrane and enhances their homotypic fusion. The mechanism of sterol-enhanced fusion is not via more efficient sorting, but instead promotes increased kinetics of fusion subreactions. We initially isolated ERG6 as a suppressor of a vrp1⌬ growth defect selective for vacuole function. VRP1 encodes verprolin, an actin-binding protein that colocalizes to vacuoles. The vrp1⌬ mutant has fragmented vacuoles in vivo and isolated vacuoles do not fuse in vitro, indicative of a Vrp1p requirement for membrane fusion. ERG6 overexpression rescues vrp1⌬ vacuole fusion in a cytosol-dependent manner. Cytosol prepared from the vrp1⌬ strain remains active; therefore, cytosol is not resupplying Vrp1p. Las17p (Vrp1p functional partner) antibodies, which inhibit wild-type vacuole fusion, do not inhibit the fusion of vacuoles from the vrp1⌬-ERG6 overexpression strain. Vacuole-associated actin turnover is decreased in the vrp1⌬ strain, but recovered by ERG6 overexpression linking sterol enrichment to actin remodeling. Therefore, the Vrp1p/Las17p requirement for membrane fusion is bypassed by increased sterols, which promotes actin remodeling as part the membrane fusion mechanism.

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“…Energy made available from the assembly of the trans-SNARE complexes is used to drive the fusion of lipid bilayers [8][9][10][11]. After membrane fusion, the adapter protein α-SNAP (soluble NSF attachment protein) and the ATPase NSF (Nethylmaleimide-sensitive factor) dissociate the cis-SNARE complexes at the expense of ATP [12,13] to free the SNAREs for the next round of membrane fusion.…”

Section: Introductionmentioning

confidence: 99%

Membrane fusion by VAMP3 and plasma membrane t-SNAREs

Hardee

Minnear

2007

Experimental Cell Research

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Pairing of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins on vesicles (v-SNAREs) and SNARE proteins on target membranes (t-SNAREs) mediates intracellular membrane fusion. VAMP3/cellubrevin is a v-SNARE that resides in recycling endosomes and endosome-derived transport vesicles. VAMP3 has been implicated in recycling of transferrin receptors, secretion of α-granules in platelets, and membrane trafficking during cell migration. Using a cell fusion assay, we examined membrane fusion capacity of the ternary complexes formed by VAMP3 and plasma membrane t-SNAREs syntaxin1, syntaxin4, SNAP-23 and SNAP-25. VAMP3 forms fusogenic pairing with t-SNARE complexes syntaxin1/SNAP-25, syntaxin1/SNAP-23 and syntaxin4/SNAP-25, but not with syntaxin4/SNAP-23. Deletion of the Nterminal domain of syntaxin4 enhanced membrane fusion more than two fold, indicating that the Nterminal domain negatively regulates membrane fusion. Differential membrane fusion capacities of the ternary v-/t-SNARE complexes suggest that transport vesicles containing VAMP3 have distinct membrane fusion kinetics with domains of the plasma membrane that present different t-SNARE proteins.

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Sec18p (NSF)-Driven Release of Sec17p (α-SNAP) Can Precede Docking and Fusion of Yeast Vacuoles

Cited by 565 publications

References 60 publications

Differential localization of syntaxin isoforms in polarized Madin-Darby canine kidney cells.

Differential localization of syntaxin isoforms in polarized Madin-Darby canine kidney cells.

Enhanced Membrane Fusion in Sterol-enriched Vacuoles Bypasses the Vrp1p Requirement

Membrane fusion by VAMP3 and plasma membrane t-SNAREs

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