Evidence for Avt6 as a vacuolar exporter of acidic amino acids in Saccharomyces cerevisiae cells.
Here we examined the significance of Avt6, a vacuolar exporter of glutamate and aspartate suggested by the in vitro membrane vesicle experiment, in vacuolar compartmentalization of amino acids in Saccharomyces cerevisiae cells. Fluorescent microscopic observation of GFP-fused Avt6 revealed it to be exclusively localized to the vacuolar membrane, with the amount of Myc-tagged Avt6 significantly increased under nitrogen starvation. Glutamate uptake by cells was enhanced by deletion of the AVT6 gene, indicating indirect involvement of Avt6 in cellular glutamate accumulation. Differences in acidic amino acid content of both total and vacuolar fractions were insignificant between the parent and avt6Delta cells when cultured in nutrient-rich conditions. However, in nitrogen-starved conditions, the amount of glutamate and aspartate in the vacuolar fraction was notably increased in the avt6Delta cells. Avt6 is thus involved in vacuolar amino acid compartmentalization in S. cerevisiae cells, especially under conditions of nitrogen starvation.
Chahomchuen
Thippayarat
T
Faculty of Agriculture, Ehime University, Matsuyama, Japan.
Hondo
Kana
K
Ohsaki
Mariko
M
Sekito
Takayuki
T
Kakinuma
Yoshimi
Y
D026905:Amino Acid Transport Systems / Q000378:metabolism*; D024342:Amino Acids, Acidic / Q000378:metabolism*; D001224:Aspartic Acid / Q000378:metabolism; D001692:Biological Transport; D003470:Culture Media; D015966:Gene Expression Regulation, Fungal; D018698:Glutamic Acid / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
D026905:Amino Acid Transport Systems; D024342:Amino Acids, Acidic; D003470:Culture Media; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D009584:Nitrogen