Abstract :
FK506, FK520 and rapamycin, produced by Streptomyces sp., Streptomyces hygroscopicus subsp. ascomyceticus and Streptomyces hygroscopicus, respectively, were observed to inhibit the growth of competing cells of the pathogenic fungus Cryptococcus neoformans and and the yeast Saccharomyces cerevisiae. Experiments involving yeast and fungal mutants were able to determine the role of FKBP12 in mediating the immunosuppressive and antimicrobial activities of the Streptomyces toxins.