Production of Novel Rapamycin Analogs by Precursor-Directed Biosynthesis

Abstract

ABSTRACT The natural product rapamycin, produced during fermentation by Streptomyces hygroscopicus , is known for its potent antifungal, immunosuppressive, and anticancer activities. During rapamycin biosynthesis, the amino acid l -pipecolate is incorporated into the rapamycin molecule. We investigated the use of precursor-directed biosynthesis to create new rapamycin analogs by substitution of unusual l -pipecolate analogs in place of the normal amino acid. Our results suggest that the l -pipecolate analog (±)-nipecotic acid inhibits the biosynthesis of l -pipecolate, thereby limiting the availability of this molecule for rapamycin biosynthesis. We used (±)-nipecotic acid in our precursor-directed biosynthesis studies to reduce l -pipecolate availability and thereby enhance the incorporation of other pipecolate analogs into the rapamycin molecule. We describe here the use of this method for production of two new sulfur-containing rapamycin analogs, 20-thiarapamycin and 15-deoxo-19-sulfoxylrapamycin, and report measurement of their binding to FKBP12.