ISOLATION AND CHARACTERIZATION OF THE AUREOBASIDIN A-RESISTANT GENE, AUR1(R), ON SCHIZOSACCHAROMYCES-POMBE - ROLES OF AUR1P(+) IN CELL MORPHOGENESIS

To study the mechanism of action of the antibiotic aureobasidin A (AbA ) on yeasts, we isolated a dominant mutant of Schizosaccharomyces pomb e which gave high resistance to AbA, From a genomic library of the mut ant, an aur1(R) mutant gene conferring AbA resistance was isolated. On e amino-acid mutation, a substitution of glycine with cysteine at resi due 240, was responsible for the acquisition of AbA resistance, The wi ld-type aur1(+) gene was essential for viability, and its over-express ion enhanced significant resistance to AbA. The predicted protein of S . pombe aur1(R) was highly homologous in primary structure and hydropa thy; profile with that of Saccharomyces cerevisiae AUR1(R) isolated as an AbA-resistance gene. To analyze a role in cell growth of S. pombe aur1(+) temperature-sensitive mutants (aur1(ts)) were obtained by rand om mutagenesis procedures using a modified PCR. The aur1(ts) mutation caused a defect in cell elongation at the non-permissive temperature a nd finally led to cell death. These results suggest that Aur1p was a t arget of the antibiotic AbA and was required in the cell elongation of cell-end tips and in the viability of S. pombe.