Divergent Biosynthetic Routes Encoded by a Single Gene Cluster in Shikimate-Derived Fungal Meroterpenoid Biosynthesis

A biosynthetic gene cluster ( tcr ) was identified from the fungus Trichothecium crotocinigenum LC36. The encoded enzymes direct the biosynthesis of two structurally distinct shikimate-originated meroterpenoids, trichothosporon A ( 1 ) and (±)-trichothecrotocin J ( 2 ), from a common precursor. Using heterologous expression and in vitro assays, the cupin-domain enzyme TcrH and the ketoreductase enzyme TcrG sequentially catalyze the dearomatization. Biochemical characterization of TcrG revealed a previously unreported cofactor-dependent substrate specificity in a ketoreductase. This work reveals novel enzymatic strategies for diversifying shikimate-derived meroterpenoid scaffolds.