The oxidative decarboxylation of prenyl 4-hydroxybenzoate to prenylhydroquinone has been frequently proposed for the biosynthesis of prenylated (hydro)quinone derivates (sometimes meroterpenoids), yet corresponding genes or enzymes remained elusive. Still unknown are the enzymes responsible for the successive decarboxylation and hydroxylation of 5-methoxy-4-hydroxy-3-hexaprenyl benzoate in the biosynthesis of yeast coenzyme Q. In addition, biosynthetic machineries usually accommodate divergent pathways to produce a dazzling array of architecturally distinct skeletons from only a handful of basic building blocks. Further insight into how structural diversity is expanded from relatively few fundamental blocks is therefore necessary to promote the development of creative approaches for the skeletal diversification of compounds.
Prof. ZENG Ying’ and Prof. LIU Jikai’ teams at the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences (CAS) investigated a monooxygenase VibMO1 involved in a divergent pathway for meroterpenoids from the basidiomycete fungus Boreostereum vibrans, in which the unprecedented and unusual pathway for vibralactone has previously been elucidated also by their teams (Angewandte Chemie International Edition 2013, 52: 2298–2302).
Research demonstrated a divergent pathway to skeletally distinct meroterpenoids in B. vibrans from a common intermediate that has a shikimate-terpenoid origin, based on the traditional platform of precursor-directed biosynthesis and the analogous intermediates resulted. Moreover, a FAD-binding monooxygenase VibMO1 was identified to convert prenyl 4-hydroxybenzoate into prenylhydroquinone and be likely involved in the biosynthesis of vibralactone G and other meroterpenoids in B. vibrans. The pathway to 3-substituted γ-butyrolactone such as vibralactone G is distinct in starting from an aryl ring of shikimate origin, which is unusual and the first time such a pathway has been described in natural product chemistry.
This study affords in vivo and in vitro verification of oxidative decarboxylation of prenyl 4-hydroxybenzoate and, subsequent to this, the important discovery of the first genetic and biochemical characterization of a FAD-binding monooxygenase VibMO1 that converts prenyl 4-hydroxybenzoate to prenylhydroquinone. This identification of VibMO1 will also be informative for the determination of enzymes essential for similar conversion steps in the biosynthesis of yeast coenzyme Q and plant meroterpenoids, where the oxidative decarboxylation of (poly)prenyl hydroxybenzoates to their hydroquinones is understood to occur yet no corresponding genes or enzymes have so far been described. This study also demonstrates divergent biosynthetic pathways toward distinct scaffolds from a single precursor. To create skeletal diversification of compounds, further insight into nature’s strategy for expanding structural diversity is needed.
The study has recently been published in Angewandte Chemie International Edition 2016, 55: 5463–5466 (http://onlinelibrary.wiley.com/doi/10.1002/anie.201510928/abstract). This work was supported by the grants from the National Natural Science Foundation of China (21572237, 81561148013). We thank Dr. Jing Yang from the Instrument Center (Kunming Institute of Botany) for determination of the absolute configuration of compound 11a.