Structural basis for acceptor-substrate recognition of UDP-glucose: anthocyanidin 3--glucosyltransferase from

Hiromoto, Takeshi; Honjo, Eijiro*; Noda, Hisanobu*; Tamada, Taro; Kazuma, Kohei*; Suzuki, Masahiko*; Blaber, M.; Kuroki, Ryota

UDP-glucose: anthocyanidin 3--glucosyltransferase (UGT78K6) from catalyzes the transfer of glucose from UDP-glucose to anthocyanidins such as delphinidin. To understand the acceptor-recognition scheme of UGT78K6, the crystal structure of UGT78K6 and its complex forms with anthocyanidin delphinidin and petunidin, and flavonol kaempferol were determined to resolutions of 1.85 , 2.55 , 2.70 and 1.75 respectively. The anthocyanidin- and flavonol-acceptor binding details are almost identical in each complex structure, although the glucosylation activities against each acceptor were significantly different. The acceptor substrates in UGT78K6 are reversely bound to its binding site by a 180 rotation about the O1-O3 axis of the flavonoid backbones observed in GT1 and UGT78G1. These substrate recognition schemes suggest the potential for controlled synthesis of natural pigments.