The vacuole of the yeast Saccharomyces cerevisiae plays an important role in nutrient storage. Arginine, in particular, accumulates in the vacuole of nitrogen-replete cells and is mobilized to the cytosol under nitrogen starvation. The arginine import and export systems involved remain poorly characterized, however. Furthermore, how their activity is coordinated by nitrogen remains unknown. Here we characterize Vsb1 as a novel vacuolar membrane protein of the APC (amino acid-polyamine-organocation) transporter superfamily which, in nitrogen-replete cells, is essential to active uptake and storage of arginine into the vacuole. A shift to nitrogen starvation causes apparent inhibition of Vsb1-dependent activity and mobilization of stored vacuolar arginine to the cytosol. We further show that this arginine export involves Ypq2, a vacuolar protein homologous to the human lysosomal cationic amino acid exporter PQLC2 and whose activity is detected only in nitrogen-starved cells. Our study unravels the main arginine import and export systems of the yeast vacuole and suggests that they are inversely regulated by nitrogen.

酵母酿酒酵母的液泡在营养物存储中起重要作用。尤其是精氨酸，在富氮细胞的液泡中积累，并在氮缺乏的情况下动员到细胞质中。但是，涉及的精氨酸进出口系统的特征仍然很差。此外，如何通过氮协调其活性尚不清楚。在这里，我们表征VSB1作为APC（一种新颖的液泡膜蛋白一个美浓酸p olyamine -有机Ç转运蛋白超家族，在富含氮的细胞中，对于精氨酸的主动摄取和储存至液泡至关重要。向氮饥饿的转移导致对Vsb1依赖性活性的明显抑制，并使储存的液泡精氨酸动员到细胞质中。我们进一步表明，该精氨酸出口涉及Ypq2，这是一种与人类溶酶体阳离子氨基酸出口商PQLC2同源的液泡蛋白，其活性仅在氮饥饿的细胞中被检测到。我们的研究揭示了酵母液泡的主要精氨酸进出口系统，并表明它们受氮反调节。