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Substrate specificity and sequence analysis define a polyphyletic origin of betanidin 5- and 6-O-glucosyltransferase from Dorotheanthus bellidiformis

Author:
Vogt, Thomas
Source:
Planta 2002 v.214 no.3 pp. 492-495
ISSN:
0032-0935
Subject:
Dorotheanthus bellidiformis, amino acid sequences, anthocyanidins, anthocyanins, betacyanins, biosynthesis, bromine, cDNA libraries, complementary DNA, flowers, glucosyltransferases, glycosylation, nucleotide sequences, proteins, sequence analysis, substrate specificity
Abstract:
Betanidin 6-O-glucosyltransferase (6-GT) is involved in the glycosylation of betacyanins, which replace the chromogenic anthocyanins as flower colorants in the Caryophyllales. The 6-GT cDNA was cloned from a cDNA library of Dorotheanthus bellidiformis (Burm. f.) N.E. Br., and the amino acid and nucleotide sequences were shown to be distinctly different from the corresponding betanidin 5-O-glucosyltransferase (5-GT) from the same plant species. Although both enzymes share very similar substrates, the proteins show only 19% amino acid sequence identity. In contrast, the protein sequence of the 6-GT showed significant identity to GTs from other species and may identify a new cluster of putative anthocyanidin GTs. Therefore, 6-GT and 5-GT apparently have evolved independently from ancestral glucosyltransferases involved in flavonoid biosynthesis.
Agid:
623399