CHARACTERIZATION OF THE SACCHAROMYCES-CEREVISIAE FMS1 GENE-RELATED TOCANDIDA-ALBICANS CORTICOSTEROID-BINDING PROTEIN-1

In order to investigate ergosterol metabolism in S. cerevisiae we stud ied the CM8 mutant strain defective in the regulation of this pathway. A genomic multicopy library was screened to reverse the CM8 phenotype . This allowed us to characterize a new gene, FMS1, which relieves mut ant phenotype by extragenic functional complementation. FMS1 may encod e a 508 amino-acid protein. The predicted protein shares 35% identity with Cbp1p, a Candida albicans corticosteroid binding-protein. Fms1p a lso shows a weaker homology with monoamine oxidases. The construction of a FMS1 null-allele yeast strain demonstrated that this gene is not essential for yeast in normal usual laboratory culture conditions. The existence of a gene related to CBP1 of C. albicans in S. cerevisiae s trongly suggests a possible function of steroid-binding proteins in ye ast general physiology rather than in a process related to pathogenici ty.