Insight into glucocorticoids glucosylation by glucosyltransferase: A combined experimental and in-silico approach

Abstract

Glucosyltransferases catalyze the glucosidic bond formation by transferring a glucose molecule from an activated sugar donor to an acceptor substrate. Glucocorticoids (GCs) are adrenal-derived steroid hormones most widely used for anti-inflammatory treatments. In this study, we biotransformed two selected GCs, cortisone and prednisone, into their O-glucoside derivatives using a versatile UDP-glycosyltransferase UGT-1. Complete structural assignment of glucosylated products revealed that the bioconversion by regio-selective glucosylation of cortisone and prednisone produced cortisone 21-glucoside and prednisone 21-glucoside, respectively. We also combined molecular dynamics (MD) simulation to study the binding feature and mechanism of glucosylation. MD simulation studies showed the formation of a stable complex between protein, glucose donor, and substrate, stabilized by hydrogen bonds. Overall, we were able to provide explanations for the experimentally observed selectivity for glucosylation by integrating experimental and computational techniques.