The yeast SLY gene products, suppressors of defects in the essential GTP-binding Ypt1 protein, may act in endoplasmic reticulum-to-Golgi transport.

Ossig, Rainer; Dascher, Christiane; Trepte, Hans-H.; Schmitt, Hans Dieter; Gallwitz, Dieter

doi:10.1128/mcb.11.6.2980

Cited by 176 publications

(167 citation statements)

References 59 publications

(67 reference statements)

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“…Both Sec22p and Sed5p show strong genetic interactions with genes encoding proteins involved in Golgi-ER retrograde transport (37,69,70). Double mutant analysis revealed that the same is true for dsl1-22.…”

Section: Dsl1p Is Required For Golgi 3 Er Traffickingmentioning

confidence: 75%

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The Coatomer-interacting Protein Dsl1p Is Required for Golgi-to-Endoplasmic Reticulum Retrieval in Yeast

Andag¹,

Neumann²,

Schmitt³

2001

Journal of Biological Chemistry

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Sec22p is an endoplasmic reticulum (ER)-Golgi v-SNARE protein whose retrieval from the Golgi compartment to the endoplasmic reticulum (ER) is mediated by COPI vesicles. Whether Sec22p exhibits its primary role at the ER or the Golgi apparatus is still a matter of debate. To determine the role of Sec22p in intracellular transport more precisely, we performed a synthetic lethality screen. We isolated mutant yeast strains in which SEC22 gene function, which in a wild type strain background is non-essential for cell viability, has become essential. In this way a novel temperature-sensitive mutant allele, dsl1-22, of the essential gene DSL1 was obtained. The dsl1-22 mutation causes severe defects in Golgi-to-ER retrieval of ER-resident SNARE proteins and integral membrane proteins harboring a Cterminal KKXX retrieval motif, as well as of the soluble ER protein BiP/Kar2p, which utilizes the HDEL receptor, Erd2p, for its recycling to the ER. DSL1 interacts genetically with mutations that affect components of the Golgi-to-ER recycling machinery, namely sec20-1, tip20-5, and COPI-encoding genes. Furthermore, we demonstrate that Dsl1p is a peripheral membrane protein, which in vitro specifically binds to coatomer, the major component of the protein coat of COPI vesicles.Membrane-bound compartments in eukaryotic cells can fuse directly as shown for the endoplasmic reticulum (ER) 1 and mitotic Golgi fragments as well as endosomal and lysosomal compartments (homotypic fusion; see Ref. 1). However, vectorial transport between distinct compartments mainly involves small coated vesicles whose formation from the donor membrane is mediated by proteinaceous coats, either COPI, COPII, or clathrin. After uncoating, vesicles fuse selectively with an acceptor membrane (heterotypic fusion; see Ref.2). Both homotypic and heterotypic fusion events rely on specific attachment reactions to guarantee that only appropriate membranes can mix. The membrane attachment itself consists of two steps, tethering and docking, involving different sets of proteins (3, 4).Tethering factors are peripherally membrane-associated protein complexes consisting of up to 10 different subunits, which share little sequence similarity.The subsequent docking stage involves specific sets of membrane-anchored proteins, so-called SNARE proteins (SNARE is soluble NSF (for N-ethylmaleimide-sensitive fusion protein) attachment protein receptor) (5-7). SNAREs are inserted into the membrane either by a C-terminal transmembrane domain or through lipid moieties attached to C-terminal cysteine residues. In contrast to the tethering factors, all known SNARE proteins are members of either of three protein families: the syntaxins, the synaptobrevins or VAMPs, and the SNAP-25 family members. To induce membrane fusion, SNARE proteins from apposed membranes must interact in trans. The formation of a stable four-helix bundle may generate enough energy to promote mixing of the lipid bilayer (8 -10).Lipid mixing experiments using SNARE complexes reconstituted into lipid bilayer vesicl...

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Section: Dsl1p Is Required For Golgi 3 Er Traffickingmentioning

confidence: 75%

“…The mutants identified were accordingly named dsl1-1 to dsl1-7 (dependent on SLY1-20). SLY1-20 is a dominant mutation, which suppresses the defects in several yeast mutants affected in ER-to-Golgi transport (27,37,(57)(58)(59)(60). Accordingly, the mutant we obtained was renamed dsl1-22.…”

Section: Dsl1p Is Required For Golgi 3 Er Traffickingmentioning

confidence: 99%

The Coatomer-interacting Protein Dsl1p Is Required for Golgi-to-Endoplasmic Reticulum Retrieval in Yeast

Andag¹,

Neumann²,

Schmitt³

2001

Journal of Biological Chemistry

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“…Several v-SNAREs with functions in traffic from the ER to the Golgi apparatus or in retrograde traffic within the Golgi apparatus have been identified in yeast: Sec22p/Sly2p, Bet1p/Sly12p, Bos1p, Sft1p, Ykt6p, and Gos1p (Newman et al, 1990;Ossig et al, 1991;McNew et al, 1997;Holthuis et al, 1998a). The v-SNAREs Snc1p and Snc2p interact with Sso1p and Sso2p in secretion (Protopopov et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

TheSaccharomyces cerevisiaev-SNARE Vti1p Is Required for Multiple Membrane Transport Pathways to the Vacuole

Mollard

Stevens

1999

MBoC

162

133

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The interaction between v-SNAREs on transport vesicles and t-SNAREs on target membranes is required for membrane traffic in eukaryotic cells. Here we identify Vti1p as the first v-SNARE protein found to be required for biosynthetic traffic into the yeast vacuole, the equivalent of the mammalian lysosome. Certain vti1-tsyeast mutants are defective in alkaline phosphatase transport from the Golgi to the vacuole and in targeting of aminopeptidase I from the cytosol to the vacuole. VTI1 interacts genetically with the vacuolar t-SNARE VAM3, which is required for transport of both alkaline phosphatase and aminopeptidase I to the vacuole. The v-SNARE Nyv1p forms a SNARE complex with Vam3p in homotypic vacuolar fusion; however, we find that Nyv1p is not required for any of the three biosynthetic pathways to the vacuole. v-SNAREs were thought to ensure specificity in membrane traffic. However, Vti1p also functions in two additional membrane traffic pathways: Vti1p interacts with the t-SNAREs Pep12p in traffic from the TGN to the prevacuolar compartment and with Sed5p in retrograde traffic to the cis-Golgi. The ability of Vti1p to mediate multiple fusion steps requires additional proteins to ensure specificity in membrane traffic.

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“…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;Kauppi et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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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The yeast SLY gene products, suppressors of defects in the essential GTP-binding Ypt1 protein, may act in endoplasmic reticulum-to-Golgi transport.

Cited by 176 publications

References 59 publications

The Coatomer-interacting Protein Dsl1p Is Required for Golgi-to-Endoplasmic Reticulum Retrieval in Yeast

The Coatomer-interacting Protein Dsl1p Is Required for Golgi-to-Endoplasmic Reticulum Retrieval in Yeast

TheSaccharomyces cerevisiaev-SNARE Vti1p Is Required for Multiple Membrane Transport Pathways to the Vacuole

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

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