title: The N-terminal domains of Vps3 and Vps8 are critical for localization and function of the CORVET tethering complex on endosomes.
abstract: Endosomal biogenesis depends on multiple fusion and fission events. For fusion, the heterohexameric CORVET complex as an effector of the endosomal Rab5/Vps21 GTPase has a central function in the initial tethering event. Here, we show that the CORVET-specific Vps3 and Vps8 subunits, which interact with Rab5/Vps21, require their N-terminal domains for localization and function. Surprisingly, CORVET may lack either one of the two N-terminal domains, but not both, to promote protein sorting via the endosome. The dually truncated complex mislocalizes to the cytosol and is impaired in endocytic protein sorting, but not in assembly. Furthermore, the endosomal localization can be rescued by overexpression of Vps21 or one of the truncated CORVET subunits, even though CORVET assembly is not impaired by loss of the N-terminal domains or in strains lacking all endosomal Rab5s and Ypt7. We thus conclude that CORVET requires only its C-terminal domains for assembly and has beyond its putative β-propeller domains additional binding sites for endosomes, which could be important to bind Vps21 and other endosome-specific factors for efficient endosome tethering.
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Epp
authors.forename: Christian
authors.initials: C
authors.lastname: Ungermann
mesh_terms: D001665:Binding Sites; D011992:Endosomes / Q000378:metabolism*; D008561:Membrane Fusion; D046912:Multiprotein Complexes / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C065531:VPS3 protein, S cerevisiae; C103153:VPS8 protein, S cerevisiae; D033921:Vesicular Transport Proteins; C086866:VPS21 protein, S cerevisiae; D020691:rab GTP-Binding Proteins