Identification of the biosynthetic gene cluster of A-500359s in Streptomyces griseus SANK60196

A-500359s, produced by Streptomyces griseus SANK60196, are inhibitors of bacterial phospho- N -acetylmuramyl-pentapeptide translocase. They are composed of three distinct moieties: a 5′-carbamoyl uridine, an unsaturated hexuronic acid and an aminocaprolactam. Two contiguous cosmids covering a 65-kb region of DNA and encoding 38 open reading frames (ORFs) putatively involved in the biosynthesis of A-500359s were identified. Reverse transcriptase PCR showed that most of the 38 ORFs are highly expressed during A-500359s production, but mutants that do not produce A-500359s did not express these same ORFs. Furthermore, orf21 , encoding a putative aminoglycoside 3′-phosphotransferase, was heterologously expressed in Escherichia coli and Streptomyces albus , yielding strains having selective resistance against A-500359B, suggesting that ORF21 phosphorylates the unsaturated hexuronic acid as a mechanism of self-resistance to A-500359s. In total, the data suggest that the cloned region is involved in the resistance, regulation and biosynthesis of A-500359s.