title: Molecular cloning and functional characterization of avaB, a gene encoding Vam6p/Vps39p-like protein in Aspergillus nidulans.
abstract: It has been demonstrated that Saccharomyces cerevisiae Vam6p/Vps39p plays a critical role in the tethering steps of vacuolar membrane fusion by facilitating guanine nucleotide exchange on small guanosine triphosphatase (GTPase) Vam4p/Ypt7p. We report here the identification and characterization of a novel protein in Aspergillus nidulans, AvaB, that exhibits similarity to Vam6p/Vps39p and plays a critical role in vacuolar morphogenesis in A. nidulans. AvaB is comprised of 1058 amino acids with amino-terminal citron homology (CNH) and central clathrin homology (CLH) domains, as observed for other Vam6p/Vps39p family proteins. Disruption of avaB in A. nidulans resulted in the fragmentation of vacuoles and reduced growth rate under various growth conditions, implying its importance in maintaining vacuolar morphology and function. Yeast two-hybrid analysis demonstrated the interaction of AvaB with AvaA, a Vam4p/Ypt7p homolog in A. nidulans, as well as the homooligomer formation of AvaB, suggesting that AvaB performs its function through hetero- or homophilic protein-protein interactions.
authors.affiliation: Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Masanao
authors.initials: M
authors.lastname: Oka
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Maruyama
authors.forename: Manabu
authors.initials: M
authors.lastname: Arioka
authors.forename: Harushi
authors.initials: H
authors.lastname: Nakajima
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kitamoto
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics; D002966:Clathrin / Q000235:genetics; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000737:chemistry / Q000302:isolation & purification; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D005800:Genes, Fungal; D007438:Introns / Q000235:genetics; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D020798:Two-Hybrid System Techniques; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000502:physiology
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D018797:Cell Cycle Proteins; D002966:Clathrin; D004271:DNA, Fungal; D005656:Fungal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C406817:VAM6 protein, S cerevisiae; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins