P148: Investigation of the Glycosylation Mechanism in the Biosynthesis of Polyene Produced by Pseudonocardia autotrophica

Polyene macrolide antifungal antibiotics including nystatin A1, amphotericin B and candicidin are produced principally by Gram-positive soil actinomycetes, and comprise a family of type I polyketide macrolide ring compounds containing 20- to 40- carbon chains, containing 3-8 conjugated double bonds. Although polyene compounds have limited clinical use, which is to be a large part due to their high toxicity and side effects, the superior antifungal activities of polyene compounds are still being considered in the development of improved antifungal drugs. Previously, we identified a novel polyene compound named NPP (Nystatin-like Pseudonocardia Polyene), which contain an aglycone identical to nystatin and harbors a unique di-sugar moiety, mycosaminyl-(a1-4)-N-acetyl-glucosamine. Compared with nystatin (which bears a single sugar moiety), the di-sugar containing NPP exhibits approximately 300-fold higher water solubility and 10-fold reduced hemolytic activity, while retaining about 50% antifungal activity against Candida albicans. To further maximize NPP potential, we analyzed P. autotrophica whole genome sequence to identify a unique glycosyltransferase present only in the NPP producing strain, P. autotrophica.  As a result, a total of 112 glycosyltransferase genes were identified from the P. autotrophica chronomosme, and some of which were predicted to be putative NPP-unique glycosyltransferase genes. Targeted gene disruption-&-complementation have been utilized to confirm functions of these putative glycosyltransferase genes. The more detailed results will be further discussed.