Biosynthesis of brevinic acid from lawsone

The menaquinone-pathway (men) is widespread in bacteria and key to the biosynthesis of intriguing small molecules such as the essential vitamin menaquinone and the natural dye lawsone. The violet molecule brevinic acid is another proposed product of men, but its direct biosynthetic precursor has remained doubtful. In this study, we isolated brevinic acid from E. coli and confirmed its non-enzymatic formation from lawsone and homocysteine involving an intermediate acetylation or phosphorylation step. We furthermore compared our proposed substrates in a non-enzymatic assay against the previously hypothesized precursor DHNA and showed that the reaction with activated lawsone derivatives proceeded faster, more selective, and with complete turnover. This supports our proposed biosynthesis of brevinic acid from lawsone and enables a cost effective, larger-scale synthesis of brevinic acid. The violet pigment brevinic acid is identified in extracts of E. coli cultures and a biosynthetic route from natural dye lawsone through phosphorylation or acetylation is presented.