Chahomchuen Thippayarat, Hondo Kana, Ohsaki Mariko, Sekito Takayuki, Kakinuma Yoshimi
Faculty of Agriculture, Ehime University, Matsuyama, Japan.
J Gen Appl Microbiol. 2009 Dec;55(6):409-17. doi: 10.2323/jgam.55.409.
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.
在此，我们研究了Avt6（一种在体外膜囊泡实验中被认为是谷氨酸和天冬氨酸液泡输出蛋白）在酿酒酵母细胞氨基酸液泡区室化中的意义。对绿色荧光蛋白（GFP）融合的Avt6进行荧光显微镜观察发现，它仅定位于液泡膜，在氮饥饿条件下，Myc标签的Avt6量显著增加。通过缺失AVT6基因可增强细胞对谷氨酸的摄取，这表明Avt6间接参与细胞内谷氨酸的积累。在营养丰富的条件下培养时，亲本细胞和avt6Delta细胞的总组分和液泡组分中酸性氨基酸含量的差异不显著。然而，在氮饥饿条件下，avt6Delta细胞液泡组分中谷氨酸和天冬氨酸的量显著增加。因此，Avt6参与酿酒酵母细胞的液泡氨基酸区室化，尤其是在氮饥饿条件下。
