Abstract
3-deoxyanthocyanins exist in limited species of mosses, ferns and higher plants. The biosynthetic pathway is partly known but the final important step on glycosylation remains uncharacterized. We tried to isolate and characterize 3-deoxyanthocyanidin 5-O-glucosyltransferase from Sinningia cardinalis plant which accumulates 3-deoxyanthocyanins such as apigeninidin 5-O-glucoside and luteolinidin 5-O-glucoside abundantly in flower petals.
By degenerated PCR, we attempted to isolate cDNA fragments of GT candidates from S. cardinalis petal cDNAs as templates. As the result, five cDNA clones designated as ScUGT1 to ScUGT5 were obtained and full-length sequence of each cDNA was determined by RACE technology. Based on the phylogenetic analysis, expression analysis by real-time RT-PCR and enzymatic assay by recombinant proteins synthesized in cell-free translation or in Escherichia coli expression system, ScUGT5 was identified as 3-deoxyanthocyanidin-specific glucosyltransferase. Namely, recombinant protein of ScUGT5 could transfer a glucosyl moiety to 3-deoxyanthocyanidins in the presence of UDP-glucose. Detailed enzymatic properties were also investigated.
