Sterol 3b-glucosyltransferase biocatalysts with a range of selectivities, including selectivity for testosterone

The main objectives of this work were to characterise a range of purified recombinant sterol 3b-glucosyltransferases and show that rational sampling of the diversity that exists within sterol 3b-glucosyltransferase sequence space can result in a range of enzyme selectivities. In our study the catalytically active domain of the Saccharomyces cerevisiae 3b-glucosyltransferase was used to mine putative sterol 3b-glucosyltransferases from the databases. Selected diverse sequences were expressed in and purified from Escherichia coli and shown to have different selectivities for the 3b-hydroxysteroids ergosterol and cholesterol. Surprisingly, three enzymes were also selective for testosterone, a 17b-hydroxysteroid. This study therefore reports for the first time sterol 3b-glucosyltransferases with selectivity for both 3band 17b-hydroxysteroids and is also the first report of recombinant 3b-glucosyltransferases with selectivity for steroids with a hydroxyl group at positions other than C-3. These enzymes could therefore find utility in the pharmaceutical industry for the green synthesis of a range of glycosylated compounds of medicinal interest.