A research group from the South China Sea Institute of Oceanology of the Chinese Academy of Sciences has revealed the enzymatic mechanism for xanthone formation in actinomycetes.
Natural products containing xanthone scaffold have shown diverse pharmacological properties. Numerous xanthones have been isolated from different sources. However, the biosynthetic mechanisms of the xanthone formation in actinomycetes is still unclear.
In this study, the researchers found that flavin binding enzyme FlsO1 from Micromonospora rosaria SCSIO N160 could catalyze multistep of oxidations (including hydroxylation, epoxidation and Baeyer-Villiger oxidation).
FlsO1 converted prejadomycin to multiple products including dehydrorabelomycin (compensating the physiological role of FlsO2), and compounds fluoxanthone A-B and fluoxanol. Using nenestatin C as the mimic substrate, FlsO1 was physiologically characterized as a benzofluorene C-5 hydrxoylase in the biosynthesis of atypical angucyclines, and a broad substrate binding cavity in the resolved crystal structure of FlsO1 explained the functional promiscuity of FlsO1.
This study provides biochemical evidence to support the physiological function of FlsO1 and reveals its underlying mechanism and structure base for the multistep of oxidations.
