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Characterization of a membrane-bound C-glucosyltransferase responsible for carminic acid biosynthesis in Dactylopius coccus Costa.

Rubini KannangaraLina SiukstaiteJonas Borch-JensenBjørn MadsenKenneth Thermann KongstadDan StaerkMads BennedsenFinn T OkkelsSilas A RasmussenThomas O LarsenRasmus J N FrandsenBirger Lindberg Møller
Published in: Nature communications (2017)
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.
Keyphrases
  • endoplasmic reticulum
  • estrogen receptor
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  • drug delivery
  • small molecule
  • dna binding
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