R. Kannangara, Lina Siukstaite, Jonas Borch-Jensen
Dec 1, 2017
Citations
2
Influential Citations
13
Citations
Journal
Nature Communications
Abstract
Carminic acid, a glucosylated anthraquinone found in scale insects like Dactylopius coccus, has since ancient times been used as a red colorant in various applications. Here we show that a membrane-bound C-glucosyltransferase, isolated from D. coccus and designated DcUGT2, catalyzes the glucosylation of flavokermesic acid and kermesic acid into their respective C-glucosides dcII and carminic acid. DcUGT2 is predicted to be a type I integral endoplasmic reticulum (ER) membrane protein, containing a cleavable N-terminal signal peptide and a C-terminal transmembrane helix that anchors the protein to the ER, followed by a short cytoplasmic tail. DcUGT2 is found to be heavily glycosylated. Truncated DcUGT2 proteins synthesized in yeast indicate the presence of an internal ER-targeting signal. The cleavable N-terminal signal peptide is shown to be essential for the activity of DcUGT2, whereas the transmembrane helix/cytoplasmic domains, although important, are not crucial for its catalytic function.Carminic acid is a widely applied red colorant that is still harvested from insects because its biosynthesis is not fully understood. Here, the authors identify and characterize a membrane-bound C-glucosyltransferase catalyzing the final step during carminic acid biosynthesis.