Analysis of the interaction of trichodiene synthase 5 (TRI5) with natural and natural-like inhibitors of trichothecene biosynthesis

The fungal pathogen Fusarium culmorum causes Fusarium head blight (FHB) on cereals, resulting in yield loss and contamination of grain with type B trichothecene mycotoxins. A key step in the synthesis of trichothecenes is catalyzed by the trichodiene synthase 5 (TRI5) that converts farnesyl pyrophosphate to trichodiene. Ferulic acid proved an efficient inhibitor of type B trichothecene biosynthesis and TRI5 gene expression in Fusarium liquid cultures. In this work several natural and natural-like compounds belonging to phenol and hydroxylated biphenyl structural classes were tested in vitro to determine their inhibitory activity towards TRI5. The recombinant TRI5 was expressed in E. coli, and the interaction with different inhibitors was analyzed by Surface Plasmon Resonance (SPR). The screening of inhibitors was performed in both direct and competitive binding format to determine which inhibitors could compete with the binding of farnesyl pyrophosphate to the enzyme active site. A combination of inhibition kinetics and computational modeling of interacting-structures may facilitate the testing of novel potential TRI5 inhibitors and the prediction of their inhibitory mechanism.