Isolation and characterization of a cDNA clone of UDP-glucose: anthocyanin 5-O-glucosyltransferase in Iris hollandica

UDP-glucose: anthocyanin 5-O-glucosyltransferase (5GT) catalyzes the transfer of the glucosyl moiety from UDP-glucose to the 5-hydroxyl group of anthocyanin. A putative full-length cDNA encoding 5GT was isolated from a cDNA library from flower buds of Iris hollandica by screening with a cDNA clone of UDP-glucose: anthocyanidin 3-O-glucosyltranseferase from Antirrhinum majus as a probe. The cDNA encodes an open reading frame of 463 amino acids with a calculated molecular mass of 50,100 Da. Heterologous expression of the cDNA in Escherichia coli demonstrated that it encoded 5GT. This is the first report of 5GT gene cloning from monocotyledonous plants. A molecular phylogenetic analysis of the amino acid sequences of glycosyltransferases from various plants showed that Ih5GT is a member of the 5GT group, although distant from dicot subgroup.