Dolichyl-phosphate-glucose is used to make O-glycans on glycoproteins of Trichomonas vaginalis.


Journal Article

Trichomonas vaginalis, the protist that causes vaginal itching, has a huge genome with numerous gene duplications. Recently we found that Trichomonas has numerous genes encoding putative dolichyl-phosphate-glucose (Dol-P-Glc) synthases (encoded by ALG5 genes) despite the fact that Trichomonas lacks the glycosyltransferases (encoded by ALG6, ALG8, and ALG10 genes) that use Dol-P-Glc to glucosylate dolichyl-PP-linked glycans. In addition, Trichomonas does not have a canonical DPM1 gene, encoding a dolichyl-P-mannose (Dol-P-Man) synthase. Here we show Trichomonas membranes have roughly 300 times the Dol-P-Glc synthase activity of Saccharomyces cerevisiae membranes and about one-fifth the Dol-P-Man synthase activity of Saccharomyces membranes. Endogenous Dol-P-hexoses of Trichomonas are relatively abundant and contain 16 isoprene units. Five paralogous Trichomonas ALG5 gene products have Dol-P-Glc synthase activity when expressed as recombinant proteins, and these Trichomonas Alg5s correct a carboxypeptidase N glycosylation defect in a Saccharomyces alg5 mutant in vivo. A recombinant Trichomonas Dpm1, which is deeply divergent in its sequence, has Dol-P-Man synthase activity. When radiolabeled Dol-P-Glc is incubated with Trichomonas membranes, Glc is incorporated into reducing and nonreducing sugars of O-glycans of endogenous glycoproteins. To our knowledge, this is the first demonstration of Dol-P-Glc as a sugar donor for O-glycans on glycoproteins.

Full Text

Duke Authors

Cited Authors

  • GrabiƄska, KA; Ghosh, SK; Guan, Z; Cui, J; Raetz, CRH; Robbins, PW; Samuelson, J

Published Date

  • August 2008

Published In

Volume / Issue

  • 7 / 8

Start / End Page

  • 1344 - 1351

PubMed ID

  • 18552282

Pubmed Central ID

  • 18552282

Electronic International Standard Serial Number (EISSN)

  • 1535-9786

Digital Object Identifier (DOI)

  • 10.1128/EC.00061-08


  • eng

Conference Location

  • United States