Efficient Acylation of Sugars and Oligosaccharides in Aqueous Environment Using Engineered Acyltransferases

A major challenge for the enzymatic synthesis of sugar esters is the low solubility of sugars in anhydrous, often toxic, organic solvents. We overcame this limitation by using acyltransferases for efficient acetylation of sugars in water. Selective 6-O-acetylation of glucose, maltose, and maltotriose with conversions of up to 78% was achieved within 15 min using engineered acyltransferases (4 mu M). Moreover, we identified EstA as a promiscuous acyltransferase preferentially acetylating sugars instead of hydrophobic acyl acceptors. This expands the applicability of promiscuous acyltransferases to sugar modifications and contributes to the understanding of how to adapt acyltransferases to hydrophilic substrates.

Automated summary

One major challenge in enzymatic synthesis of sugar esters is the low solubility of sugars in toxic organic solvents. This study demonstrated efficient acetylation of sugars in water using engineered acyltransferases, achieving high conversion rates for glucose, maltose, and maltotriose. The discovery of EstA as a promiscuous acyltransferase that preferentially acetylates sugars expands the potential applications of such enzymes in sugar modifications.