A link between ER tethering and COP-I vesicle uncoating.
The yeast Dsl1p vesicle tethering complex, comprising the three subunits Dsl1p, Dsl3p, and Tip20p, is stably associated with three endoplasmic reticulum-localized Q-SNAREs and is believed to play a central role in the tethering and fusion of Golgi-derived COP-I transport vesicles. Dsl1p also interacts directly with COP-I subunits. We now show that binding of Dsl1p to COP-I subunits involves binding sites identical to those involved in interactions between COP-I subunits that stabilize the COP-I coat. Cells with defects in Dsl/SNARE complex function show massive accumulation of COP-I-coated vesicles in a cluster to which COP-II coat proteins are also recruited. Our results suggest that binding of Dsl/SNARE complex to the COP-I coat complex serves two functions: to mediate vesicle tethering and to assist the uncoating process by blocking domains in COP-I that drive repolymerization and the formation of large COP-I aggregates.
Zink
Sabrina
S
Department Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, D37077, Germany.
Wenzel
Dirk
D
Wurm
Christian A
CA
Schmitt
Hans Dieter
HD
D001665:Binding Sites; D020755:Coat Protein Complex I / Q000378:metabolism*; D015536:Down-Regulation; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D008957:Models, Genetic; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D020755:Coat Protein Complex I; C428365:DSL1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005982:Glutathione Transferase