Anthocyanin 5,3′-aromatic acyltransferase from Gentiana triflora, a structural insight into biosynthesis of a blue anthocyanin

The acylation of anthocyanins contributes to their structural diversity. Aromatic is responsible for the blue color and certain flowers. acyltransferase from Gentiana triflora Pall. (Gentianaceae) (Gt5,3′AT) catalyzes glucosyl moieties at 5 3′ positions anthocyanins. Anthocyanin transfers an acyl group a single position, such that Gt5,3′AT possesses unique enzymatic activity. Structural investigation this aromatic transfer fundamental understand molecular mechanism double positions. In study, analyses were conducted identify underlying mechanism. crystal structure indicated shares similarities with other BAHD family enzymes, consisting N C terminal lobes. comparison revealed preference (aromatic or aliphatic) enzymes was determined by four amino acid positions, which are well conserved in aliphatic CoA-binding acyltransferases. Although complex not obtained, binding delphinidin 3,5,3′-triglucoside investigated evaluating dynamics. simulation preferentially occurs 5-position rather than 3′-position, interacting acids mainly located C-terminal lobe. Subsequent assays chimeric (exchange N-terminal lobe between lisianthus anthocyanin 5AT) demonstrated selectivity may be caused