title: Glu-44 in the amino-terminal α-helix of yeast vacuolar ATPase E subunit (Vma4p) has a role for VoV1 assembly.
abstract: The proton (H(+)) pumping vacuolar-type ATPase (V-ATPase) is a rotary enzyme that plays a pivotal role in forming intracellular acidic compartments in eukaryotic cells. In Saccharomyces cerevisiae, the membrane extrinsic catalytic V1 and the transmembrane proton-pumping Vo complexes have been shown to reversibly dissociate upon removal of glucose from the medium. However, the basis of this disassembly is largely unknown. In the earlier study, we have found that the amino-terminal α-helical domain between Lys-33 and Lys-83 of yeast E subunit (Vma4p) in the peripheral stalk of the V1 complex has a role in glucose-dependent VoV1 assembly. Results of alanine-scanning mutagenesis within the domain revealed that the Vma4p Glu-44 is a key residue in VoV1 disassembly. Biochemical analysis on Vma4p Glu-44 to Ala, Asn, Asp, and Gln substitutions indicated that Glu-44 has a role in V-ATPase catalysis. These results suggest that Glu-44 is one of the key functional residues for subunit interaction in the V-ATPase stalk complex that allows both efficient rotation catalysis and assembly.
authors.affiliation: From the Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694, Japan.
authors.forename: Haruko
authors.initials: H
authors.lastname: Okamoto-Terry
authors.forename: Kaori
authors.initials: K
authors.lastname: Umeki
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nakanishi-Matsui
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Futai
mesh_terms: D000595:Amino Acid Sequence; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C500733:Vma4 protein, S cerevisiae; D018698:Glutamic Acid; D025262:Vacuolar Proton-Translocating ATPases; D005947:Glucose
keywords: Bioenergetics; Confocal Microscopy; Enzyme Catalysis; Protein Assembly; V-ATPase; Yeast