A Candida albicans oligopeptide transport gene, OPT1, was cloned from a C. albicans genomic library through heterologous expression in the Saccharomyces cerevisiae di-/tripeptide transport mutant PB1X-9B. When transformed with a plasmid harboring OPT1, S. cerevisiae PB1X-9B, which did not express tetra-/pentapeptide transport activity under the conditions used, was conferred with an oligopeptide transport phenotype as indicated by growth on the tetrapeptide Lysyl-Leucyl-Leucyl-Glycine, sensitivivity to toxic tetra- and pentapeptides, and an increase in the initial uptake rate of the radiolabeled tetrapeptide Lysyl-Leucyl-Glycyl-[3H]Leucine. The entire 3.8 kb fragment containing the oligopeptide transport activity was sequenced and an open reading frame of 2349 nucleotides containing a 58 nucleotide intron was identified. The deduced protein product of 783 amino acid residues contained twelve hydrophobic regions suggestive of a membrane transport protein. The oligopeptide transporter facilitates targeting of antifungal, especially anticandidal drugs.
展开▼
