Organisation of the Biosynthetic Gene Cluster and Tailoring Enzymes in the Biosynthesis of the Tetracyclic Quinone Glycoside Antibiotic Polyketomycin

Surprising results regarding the function of methyltransferases and oxygenases: Investigations on oxygenase and methyltransferase genes that are located in the polyketomycin biosynthetic gene cluster of Streptomyces diastatochromogenes Tü6028 shed light into polyketide‐modifying reactions. magnified image Polyketomycin is a tetracyclic quinone glycoside produced by Streptomyces diastatochromogenes Tü6028. It shows cytotoxic and antibiotic activity, in particular against Gram‐positive multi‐drug‐resistant strains (for example, MRSA). The polyketomycin biosynthetic gene cluster has been sequenced and characterised. Its identity was proven by inactivation of a α‐ketoacyl synthase gene (pokP1) of the “minimal polyketide synthase II” system. In order to obtain valuable information about tailoring steps, we performed further gene‐inactivation experiments. The generation of mutants with deletions in oxygenase genes (pokO1, pokO2, both in parallel and pokO4) and methyltransferase genes (pokMT1, pokMT2 and pokMT3) resulted in new polyketomycin derivatives, and provided information about the organisation of the biosynthetic pathway.