Resolution of (+)-abscisic acid using an Arabidopsis glycosyltransferase

Abstract

Abscisic acid (ABA) can exist as two enantiomers, with (+)-ABA as the naturally occurring form. Typically, both enantiomers occur in chemical preparations and both can be modified in the plant to their respective glucose esters. To identify glycosyltransferases capable of discriminating between the different forms of ABA, the Family 1 enzymes of Arabidopsis thaliana were screened for activity towards (±)-ABA. Eight enzymes were found to recognise the plant hormone, with one UGT71B6 showing enantioselective glucosylation towards (+)-ABA. UGT71B6 was used in a whole-cell biocatalysis system as a means of separating (+)- and (−)-ABA, thereby offering an alternative to chemical synthesis for the production of pure (+)-ABA.