Identification of the fnxl+ and fnx2+ genes for vacuolar amino acid transporters in Schizosaccharomyces pombe

We have identified the Schizosaccharonvees pombe SPBC3E7.06c gene (fnx2(+)) from a homology search with the fiix1(+) gene involving in G(0) arrest upon nitrogen starvation. Green fluorescent protein-fused Fnx1p and Fnx2p localized exclusively to the vacuolar membrane. Uptake of histidine or isoleucine by S. pombe cells was inhibited by concanamycin A, a specific inhibitor of the vacuolar H+-ATPase. Amino acid uptake was also defective in the vacuolar ATPase mutant, suggesting that vacuolar compartmentalization is critical for amino acid uptake by whole cells. In both Delta fnx1 and Delta fnx2 mutant cells, uptake of lysine, isoleucine or asparagine was impaired. These results suggest that Jnx1(+) and fnx2(+) are involved in vacuolar amino acid uptake in S. pombe. (C) 2008 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.