Characterization\nof the Flavin-Dependent Monooxygenase\nInvolved in the Biosynthesis of the Nocardiosis-Associated Polyketide

Some species of the <i>Nocardia</i> genus harbor\na highly\nconserved biosynthetic gene cluster designated as the NOCardiosis-Associated\nPolyketide (NOCAP) synthase that produces a unique glycolipid natural\nproduct. The NOCAP glycolipid is composed of a fully substituted benzaldehyde\nheadgroup linked to a polyfunctional alkyl tail and an <i>O</i>-linked disaccharide composed of 3-α-epimycarose and 2-<i>O</i>-methyl-α-rhamnose. Incorporation of the disaccharide\nunit is preceded by a critical step involving hydroxylation by NocapM,\na flavin monooxygenase. In this study, we employed biochemical, spectroscopic,\nand kinetic analyses to explore the substrate scope of NocapM. Our\nfindings indicate that NocapM catalyzes hydroxylation of diverse aromatic\nsubstrates, although the observed coupling between NADPH oxidation\nand substrate hydroxylation varies widely from substrate to substrate.\nOur in-depth biochemical characterization of NocapM provides a solid\nfoundation for future mechanistic studies of this enzyme as well as\nits utilization as a practical biocatalyst.