Abyssomicin C and its atropisomer are potent inhibitors of bacterial folate metabolism. They possess complex polycyclic structures, and their biosynthesis has been shown to involve several unusual enzymatic transformations. Using a combination of synthesis and in vitro assays we reveal that AbyV, a cytochrome P450 enzyme from the aby gene cluster, catalyses a key late-stage epoxidation required for the installation of the characteristic ether-bridged core of abyssomicin C. The X-ray crystal structure of AbyV has been determined, which in combination with molecular dynamics simulations provides a structural framework for our functional data. This work demonstrates the power of combining selective carbon-13 labelling with NMR spectroscopy as a sensitive tool to interrogate enzyme-catalysed reactions in vitro with no need for purification.
The cytochrome P450 enzyme AbyV catalyses a key epoxidation in the final stages of the biosynthesis of the spirotetronate antibiotic abyssomicin C. Combining structural and computational data with a 13C labelling strategy was found to be a powerful approach to interrogate the biotransformation and determine the precise function of the enzyme.
Keywords: Antibiotics; Biosynthesis; P450 Enzymes; Polyketides; Structure Elucidation.
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