Vps52p, Vps53p, and Vps54p Form a Novel Multisubunit Complex Required for Protein Sorting at the Yeast Late Golgi

Abstract

The late Golgi of the yeast Saccharomyces cerevisiae receives membrane traffic from the secretory pathway as well as retrograde traffic from post-Golgi compartments, but the machinery that regulates these vesicle-docking and fusion events has not been characterized. We have identified three components of a novel protein complex that is required for protein sorting at the yeast late Golgi compartment. Mutation of VPS52, VPS53, or VPS54 results in the missorting of 70% of the vacuolar hydrolase carboxypeptidase Y as well as the mislocalization of late Golgi membrane proteins to the vacuole, whereas protein traffic through the early part of the Golgi complex is unaffected. A vps52/53/54 triple mutant strain is phenotypically indistinguishable from each of the single mutants, consistent with the model that all three are required for a common step in membrane transport. Native coimmunoprecipitation experiments indicate that Vps52p, Vps53p, and Vps54p are associated in a 1:1:1 complex that sediments as a single peak on sucrose velocity gradients. This complex, which exists both in a soluble pool and as a peripheral component of a membrane fraction, colocalizes with markers of the yeast late Golgi by immunofluorescence microscopy. Together, the phenotypic and biochemical data suggest that VPS52, VPS53, and VPS54 are required for the retrograde transport of Golgi membrane proteins from an endosomal/ prevacuolar compartment. The Vps52/53/54 complex joins a growing list of distinct multisubunit complexes that regulate membrane-trafficking events.

Mutants defective in secretory/vacuolar pathways in the EUROFAN collection of yeast disruptants

“…Cells lacking these proteins display high levels of CPY secretion and defects in the stability and distribution of several late Golgi proteins, including the Vps10p CPY receptor. Vps52p, Vps53p and Vps54p are thought to be required for correct retrograde sorting from the PVC back to the late Golgi compartment (Conibear and Stevens, 2000).…”

“…It is not yet entirely clear whether this pathway originates from early or late endosomes (Galan et al, 2001;Lewis et al, 2000;Panek et al, 2000;Wiederkehr et al, 2000). The distribution of Tlg2p has been reported to overlap with those of TGN and endosomal markers (Abeliovich et al, 1998;Conibear and Stevens, 2000;Holthuis et al, 1998;Panek et al, 2000;Séron et al, 1998).…”

TheDrosophila Cog5Homologue Is Required for Cytokinesis, Cell Elongation, and Assembly of Specialized Golgi Architecture during Spermatogenesis

“…The exocyst (sec6/8 complex), composed of eight proteins, is thought to help recruit Golgiderived vesicles to the plasma membrane at the final step of the secretory pathway (Hsu et al, 1996;TerBush et al, 1996;Kee et al, 1997). The multisubunit TRAPP I and Vps52/ 53/54 complexes are believed to serve analogous functions during ER-to-Golgi and endosome-to-Golgi trafficking, respectively (Conibear and Stevens, 2000;Sacher et al, 2001). The eight-component mammalian conserved oligomeric Golgi (COG) complex and the homologous Sec34/35 complex in yeast have been proposed to assist in Golgi vesicle targeting VanRheenen et al, 1998;Walter et al, 1998;VanRheenen et al, 1999;Sacher et al, 2001;Whyte and Munro, 2001;Ungar et al, 2002).…”

HCCS1 overexpression induces apoptosis via cathepsin D and intracellular calcium, and HCCS1 disruption in mice causes placental abnormality

“…In yeast, Vps53 is a subunit of the Golgi-associated retrograde protein complex, which is involved in retrograde transport from the early and late endosome to the late Golgi. 26 Human Vps53 or HCCS1 was shown to have analogous characteristics to the yeast homologue and co-localized with mannose-6-phosphate receptor, 27 which is the primary receptor for the lysosomal aspartyl protease cathepsin D. 28 Based on these observations, one may conceive that overexpressed HCCS1 induces the efflux of cathepsin D by executing an abnormal transport function in the endosomal/lysosomal system. However, the mechanism by which overexpressed HCCS1 induces the elevation of intracellular calcium is not yet clear.…”