Resveratrol improves fungal ribosylation capacity through a unique mechanism

Abstract

Ribosylation is a significant modification conferring new complex and broadened cellular roles of compounds, but small organic molecules are rarely ribosylated. Here, we report the 3-O- and 4′-O-α-ribosylation of resveratrol, a phytoalexin that is exogenous to the fungus Daldinia eschscholzii IFB-TL01. The ribosylation is mechanistically due to the resveratrol-activated expression of the silent or less active fungal genes governing the ribosylation of non-fungal phytophenols. The resveratrol-induced ribosylation is also characterized by an increased expression of ribosyltransferases in concert with a rare ribosylating reaction using nicotinamide mononucleotide (NMN) as a ribose donor. The ribosylation-reduced toxicity of resveratrol to D. eschscholzii, along with the involvement of at least two p-glycoproteins in the glycosylation, suggests that such a glycosylation process may be a general strategy for the fungal detoxification of phenolic chemicals. The findings present an updated view of the ribosylation of small molecules, and provide direct chemogenetic evidence that will aid understanding of how phytophenols such as resveratrol function differently in the plant, microbial and animal kingdoms.