Abstract
Vacuoles are the compartment of amino acids in yeast as well as in plant cells. Several transport systems operate in the Saccharomyces cerevisiae vacuole. Concanamycin A, an inhibitor of the vacuolar H+-ATPase, inhibited uptake of amino acids but not of 2-Deoxy-D-glucose by Schizosaccharomyces pombe cells, suggesting involvement of vacuole in amino acid uptake by cells. We found that S. pombe fnx1 (SPBC21D10.04c) and fnx2 (SPBC3E7.06c) genes are phylogenetically related to S. cerevisiae VBA2 (YBR293w) gene encoding vacuolar basic amino acid transporter. GFP-fused Fnx1p and Fnx2p localized exclusively to the vacuolar membrane of S. pombe. Uptake of lysine, asparagine or isoleucine was impaired by Δfnx1 mutant cells whereas uptake of lysine or isoleucine impaired by Δfnx2 mutant. These results suggest that Fnx1p and Fnx2p are involved in vacuolar transport by S. pombe with a moderate specificity for amino acids.
