USE OF THE PDR4 GENE AS A DOMINANT SELECTIVE MARKER IN COMBINATION WITH CERULENIN FOR PROTOTROPHIC STRAINS IN SACCHAROMYCES-CEREVISIAE

We found that a 2.1-kbp KpnI fragment bearing the PDR4 (YAP1/PAR1/SNQ3) gene of Saccharomyces cerevisiae, conferring pleiotropic drug resistance to S. cerevisiae, confers resistance of the cells to 5 mug of cerulenin per ml when ligated into a multicopy vector and to 1 mug of cerulenin ligated into a single copy vector. This 2.1-kbp KpnI fragment lacks the C-terminal coding region of the published nucleotide sequence (Hussain, M. and Lenard, J.: Gene, 101, 149-152, 1991). This dosage-dependent cerulenin resistance induced by the 2.1-kbp KpnI fragment of PDR4 is useful as a dominant selective marker in genetic studies and in transformation of prototrophic S. cerevisiae strains. We constructed a pair of tester strains for mating-type determination by introducing the multicopy plasmid bearing the 2.1-kbp KpnI fragment into a and a haploid strains of S. cerevisiae.