title: Functional Expression and Characterization of Schizosaccharomyces pombe Avt3p as a Vacuolar Amino Acid Exporter in Saccharomyces cerevisiae.
abstract: In Saccharomyces cerevisiae, Avt3p and Avt4p mediate the extrusion of several amino acids from the vacuolar lumen into the cytosol. SpAvt3p of Schizosaccharomyces pombe, a homologue of these vacuolar amino acid transporters, has been indicated to be involved in spore formation. In this study, we confirmed that GFP-SpAvt3p localized to the vacuolar membrane in S. pombe. The amounts of various amino acids increased significantly in the vacuolar pool of avt3Δ cells, but decreased in that of avt3+-overexpressing avt3Δ cells. These results suggest that SpAvt3p participates in the vacuolar compartmentalization of amino acids in S. pombe. To examine the export activity of SpAvt3p, we expressed the avt3+ gene in S. cerevisiae cells. We found that the heterologously overproduced GFP-SpAvt3p localized to the vacuolar membrane in S. cerevisiae. Using the vacuolar membrane vesicles isolated from avt3+-overexpressing S. cerevisiae cells, we detected the export activities of alanine and tyrosine in an ATP-dependent manner. These activities were inhibited by the addition of a V-ATPase inhibitor, concanamycin A, thereby suggesting that the activity of SpAvt3p is dependent on a proton electrochemical gradient generated by the action of V-ATPase. In addition, the amounts of various amino acids in the vacuolar pools of S. cerevisiae cells were decreased by the overproduction of SpAvt3p, which indicated that SpAvt3p was functional in S. cerevisiae cells. Thus, SpAvt3p is a vacuolar transporter that is involved in the export of amino acids from S. pombe vacuoles.
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Soracom
authors.initials: S
authors.lastname: Chardwiriyapreecha
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Manabe
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Iwaki
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kawano-Kawada
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sekito
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Siriporn
authors.initials: S
authors.lastname: Lunprom
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Akiyama
authors.affiliation: Laboratory of Applied Microbiology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takegawa
authors.affiliation: Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kakinuma
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport; D015151:Immunoblotting; D007425:Intracellular Membranes; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D026905:Amino Acid Transport Systems; D000596:Amino Acids; D029702:Schizosaccharomyces pombe Proteins; D000251:Adenosine Triphosphatases