title: The Dsl1 protein tethering complex is a resident endoplasmic reticulum complex, which interacts with five soluble NSF (N-ethylmaleimide-sensitive factor) attachment protein receptors (SNAREs): implications for fusion and fusion regulation.
abstract: Retrograde vesicular transport from the Golgi to the ER requires the Dsl1 tethering complex, which consists of the three subunits Dsl1, Dsl3, and Tip20. It forms a stable complex with the SNAREs Ufe1, Use1, and Sec20 to mediate fusion of COPI vesicles with the endoplasmic reticulum. Here, we analyze molecular interactions between five SNAREs of the ER (Ufe1, Use1, Sec20, Sec22, and Ykt6) and the Dsl1 complex in vitro and in vivo. Of the two R-SNAREs, Sec22 is preferred over Ykt6 in the Dsl-SNARE complex. The NSF homolog Sec18 can displace Ykt6 but not Sec22, suggesting a regulatory function for Ykt6. In addition, our data also reveal that subunits of the Dsl1 complex (Dsl1, Dsl3, and Tip20), as well as the SNAREs Ufe1 and Sec20, are ER-resident proteins that do not seem to move into COPII vesicles. Our data support a model, in which a tethering complex is stabilized at the organelle membrane by binding to SNAREs, recognizes the incoming vesicle via its coat and then promotes its SNARE-mediated fusion.
authors.affiliation: Department of Biology and Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany.
authors.forename: Christoph T A
authors.initials: CT
authors.lastname: Meiringer
authors.forename: Ralf
authors.initials: R
authors.lastname: Rethmeier
authors.forename: Kathrin
authors.initials: K
authors.lastname: Auffarth
authors.forename: Joshua
authors.initials: J
authors.lastname: Wilson
authors.forename: Angela
authors.initials: A
authors.lastname: Perz
authors.forename: Charles
authors.initials: C
authors.lastname: Barlowe
authors.forename: Hans Dieter
authors.initials: HD
authors.lastname: Schmitt
authors.forename: Christian
authors.initials: C
authors.lastname: Ungermann
mesh_terms: D022181:COP-Coated Vesicles / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology*; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C428365:DSL1 protein, S cerevisiae; D046912:Multiprotein Complexes; D021122:Protein Subunits; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins