A Family of Basic Amino Acid Transporters of the Vacuolar Membrane from Saccharomyces cerevisiae

Abstract

Among the members of the major facilitator superfamily of Saccharomyces cerevisiae, we identified genes involved in the transport into vacuoles of the basic amino acids histidine, lysine, and arginine. ATP-dependent uptake of histidine and lysine by isolated vacuolar membrane vesicles was impaired in YMR088c, a vacuolar basic amino acid transporter 1 (VBA1)-deleted strain, whereas uptake of tyrosine or calcium was little affected. This defect in histidine and lysine uptake was complemented fully by introducing the VBA1 gene and partially by a gene encoding Vba1p fused with green fluorescent protein, which was determined to localize exclusively to the vacuolar membrane. A defect in the uptake of histidine, lysine, or arginine was also observed in the vacuolar membrane vesicles of mutants YBR293w (VBA2) and YCL069w (VBA3). These three VBA genes are closely related phylogenetically and constitute a new family of basic amino acid transporters in the yeast vacuole.

Heptahelical protein PQLC2 is a lysosomal cationic amino acid exporter underlying the action of cysteamine in cystinosis therapy

“…1D). A previous study reported that uptake of the three proteinogenic CAAs into the yeast vacuole is mediated by the Vba1, Vba2, and Vba3 transporters from the major facilitator superfamily (33). In a triple vba mutant, the Ypq2-dependent canavanine resistance phenotype is abolished (Fig.…”

Identification of the fnx1+ and fnx2+ genes for vacuolar amino acid transporters in Schizosaccharomyces pombe

“…The authors in the previous paper [9] speculated, without any data on its cellular localization, that Fnx1p was the plasma membrane H + /drug antiporter involved in drug resistance [9]. In this paper, we focused on the similarity of fnx1 + to S. cerevisiae VBA2, which encodes a vacuolar H + /amino acid antiporter [8], and characterized Fnx1p, as well as the related Fnx2p, as vacuolar transporters in S. pombe. Although we did not reproduce the drug sensitivity of Dfnx1 mutant as reported previously [9] (data not shown), the phenotype of the Dfnx1 mutant to these drugs may be explained by sequestering of the toxic compounds into vacuoles.…”

“…We hypothesized that Fnx1p and Fnx2p might function to mediate amino acid uptake into vacuoles, especially for basic amino acids, based on the phylogenetic relationship with S. cerevisiae Vba2p, a vacuolar transporter for basic amino acids (Fig. 1) [8]. As shown in Fig.…”

“…On the basis of results from kinetics experiments with vacuolar membrane vesicles from Saccharomyces cerevisiae [4], seven uptake systems for amino acids have been proposed. Recently two gene families, AVT and vacuolar transporter for basic amino acids (VBA), were found to be involved in amino acid transport in the S. cerevisiae vacuole [7,8]. In the AVT family, AVT1 is involved in uptake of neutral amino acids, and AVT3 and AVT4 in the extrusion of these amino acids from vacuoles [7].…”

“…In the AVT family, AVT1 is involved in uptake of neutral amino acids, and AVT3 and AVT4 in the extrusion of these amino acids from vacuoles [7]. All the members of the VBA family, VBA1, VBA2 and VBA3, are involved in the uptake of basic amino acids into vacuoles [8]. However, it is unlikely that all amino acid transport in S. cerevisiae vacuole is performed by these proteins.…”