Cloning and characterization of a Myxococcus xanthus cytochrome P-450 hydroxylase required for biosynthesis of the polyketide antibiotic TA

The antibiotic TA, a complex macrocyclic polyketide of Myxococcus xanthus, is produced, like many other polyketides, through successive condensations of acetate by a type I polyketide synthase (PKS) mechanism. The chemical st ructure of this antibiotic and the mechanism by which it is synthesized ind icate the need for several post-modification steps, such as a specific hydr oxylation at C-20. Previous studies have shown that several genes, essentia l for TA biosynthesis, are clustered in a region of at least 36 kb, which w as subsequently cloned and analyzed. In this study, we report the analysis of a DNA fragment, containing a specific cytochrome P-450 hydroxylase, pres umably responsible for the sole non-PKS hydroxylation at position C-20. Fun ctional analysis of the cytochrome P-450 hydroxylase gene through specific gene disruption confirms that it is essential for the production of an acti ve TA molecule. (C) 1999 Elsevier Science B.V. All rights reserved.