The diversity of dolichol-linked precursors to Asn-linked glycans likely results from secondary loss of sets of glycosyltransferases
Department of Biochemistry and Molecular Pharmacology, Department of Neurobiology University of Massachusetts Medical School
Medical Subject Headings
Animals; *Asparagine; Bacteria; Computational Biology; Dolichol; Evolution, Molecular; *Genetic Variation; Glycopeptides; Glycosyltransferases; Humans; Polysaccharides; Species Specificity
The vast majority of eukaryotes (fungi, plants, animals, slime mold, and euglena) synthesize Asn-linked glycans (Alg) by means of a lipid-linked precursor dolichol-PP-GlcNAc2Man9Glc3. Knowledge of this pathway is important because defects in the glycosyltransferases (Alg1-Alg12 and others not yet identified), which make dolichol-PP-glycans, lead to numerous congenital disorders of glycosylation. Here we used bioinformatic and experimental methods to characterize Alg glycosyltransferases and dolichol-PP-glycans of diverse protists, including many human pathogens, with the following major conclusions. First, it is demonstrated that common ancestry is a useful method of predicting the Alg glycosyltransferase inventory of each eukaryote. Second, in the vast majority of cases, this inventory accurately predicts the dolichol-PP-glycans observed. Third, Alg glycosyltransferases are missing in sets from each organism (e.g., all of the glycosyltransferases that add glucose and mannose are absent from Giardia and Plasmodium). Fourth, dolichol-PP-GlcNAc2Man5 (present in Entamoeba and Trichomonas) and dolichol-PP- and N-linked GlcNAc2 (present in Giardia) have not been identified previously in wild-type organisms. Finally, the present diversity of protist and fungal dolichol-PP-linked glycans appears to result from secondary loss of glycosyltransferases from a common ancestor that contained the complete set of Alg glycosyltransferases.
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Citation: Proc Natl Acad Sci U S A. 2005 Feb 1;102(5):1548-53. Epub 2005 Jan 21. Link to article on publisher's site
Samuelson, John; Banerjee, Sulagna; Magnelli, Paula; Cui, Jike; Kelleher, Daniel J.; Gilmore, Reid; and Robbins, Phillips W., "The diversity of dolichol-linked precursors to Asn-linked glycans likely results from secondary loss of sets of glycosyltransferases" (2005). Biochemistry and Molecular Pharmacology Publications and Presentations. 184.