The Fenpropimorph Resistance Gene FEN2 fromSaccharomyces cerevisiae Encodes a Plasma Membrane H+-Pantothenate Symporter

The product of the FEN2 gene of Saccharomyces cerevisiae has previously been described as a protein conferring sensitivity to the antifungal agent fenpropimorph. Fen2p was postulated to act as a common regulator of carbon and nitrogen catabolite repression and of amino acid and ergosterol biosynthesis. In this paper, we present experimental evidence characterizing Fen2p as a plasma membrane-localized transporter for the vitamin pantothenate. The high affinity transport system (Km = 3.5 microM) is sensitive to uncouplers, suggesting a H+-pantothenate cotransport. Pantothenate transport rates in yeast are modulated by extracellular pantothenate, being maximal at low pantothenate concentrations. It is demonstrated that beta-alanine can suppress the growth defect of FEN2 wild-type and fen2 mutant cells on pantothenate-free medium. Evidence is presented that beta-alanine is transported by the general amino acid permease Gap1p. The relation among pantothenate transport, nitrogen catabolite repression, and sensitivity to the antifungal agent fenpropimorph is discussed.