Biosynthesis of Biscognienyne B Involving a Cytochrome P450‐Dependent Alkynylation

Abstract

The alkyne is a biologically significant moiety found in many natural products and a versatile functional group widely used in modern chemistry. Recent studies have revealed the biosynthesis of acetylenic bonds in fatty acids and amino acids. However, the molecular basis for the alkynyl moiety in acetylenic prenyl chains occurring in a number of meroterpenoids remains obscure. Here, we identify the biosynthetic gene cluster and characterize the biosynthetic pathway of an acetylenic meroterpenoid biscognienyne B based on heterologous expression, feeding experiments, and in vitro assay. This work shows that the alkyne moiety is constructed by an unprecedented cytochrome P450 enzyme BisI, which shows promiscuous activity towards C5 and C15 prenyl chains. This finding provides an opportunity for discovery of new compounds, featuring acetylenic prenyl chains, through genome mining, and it also expands the enzyme inventory for de novo biosynthesis of alkynes.

Biosynthesis of alkyne-containing natural products

“…9A ). 22 Particularly, they found that the alkyne in 28 was installed by the cytochrome P450 enzyme BisI, which is different from the other reported enzymes dedicated to acetylenic bond biosynthesis. In order to explore the mechanism and substrate scope of the BisI-mediated biosynthesis of the alkynyl moiety, the authors chemically prepared the 1-OH methylated form ( 31 ) of 4-hydroxy-3-prenylbenzoic acid and performed feeding experiments ( Fig.…”

“… 74,75 Recently, two research groups simultaneously reported that the alkynyl moieties in the prenyl chains of biscognienyne B ( 28 ) and asperpentyn ( 29 ) are generated by cytochrome P450 enzymes, as determined via heterologous expression, feeding experiments and in vitro enzyme reactions. 22,23 Furthermore, the two groups demonstrated that the stereochemistry of the double bond in the intermediates is important for substrate recognition.…”

“…However, further feeding experiments and in vitro assays revealed that BisI cannot accept 32 or its demethylated derivative 33 as a substrate to yield the corresponding acetylenic products, but it shows promiscuous activities towards C5 and C15 prenyl chains. 22 …”

Peculiarities of meroterpenoids and their bioproduction

“…Heterologous expression, feeding experiments, and in vitro assays were used to characterize the biosynthetic pathway. Specifically, an novel cytochrome P450-dependent BisI was shown to be involved in alkynylation of the prenyl chain (Lv et al 2020) (Fig. S11).…”