Unique Asn-linked oligosaccharides of the human pathogen Entamoeba histolytica
Department of Biochemistry and Molecular Pharmacology, Department of Neurobiology University of Massachusetts Medical School
Medical Subject Headings
Animals; Asparagine; Concanavalin A; Endoplasmic Reticulum; Entamoeba histolytica; *Gene Expression Regulation; Glycosylation; Lectins; Mass Spectrometry; Models, Chemical; Molecular Conformation; Oligosaccharides; Polysaccharides; Protein Folding; alpha-Mannosidase
N-Glycans of Entamoeba histolytica, the protist that causes amebic dysentery and liver abscess, are of great interest for multiple reasons. E. histolytica makes an unusual truncated N-glycan precursor (Man(5)GlcNAc(2)), has few nucleotide sugar transporters, and has a surface that is capped by the lectin concanavalin A. Here, biochemical and mass spectrometric methods were used to examine N-glycan biosynthesis and the final N-glycans of E. histolytica with the following conclusions. Unprocessed Man(5)GlcNAc(2), which is the most abundant E. histolytica N-glycan, is aggregated into caps on the surface of E. histolytica by the N-glycan-specific, anti-retroviral lectin cyanovirin-N. Glc(1)Man(5)GlcNAc(2), which is made by a UDP-Glc: glycoprotein glucosyltransferase that is part of a conserved N-glycan-dependent endoplasmic reticulum quality control system for protein folding, is also present in mature N-glycans. A swainsonine-sensitive alpha-mannosidase trims some N-glycans to biantennary Man(3)GlcNAc(2). Complex N-glycans of E. histolytica are made by the addition of alpha1,2-linked Gal to both arms of small oligomannose glycans, and Gal residues are capped by one or more Glc. In summary, E. histolytica N-glycans include unprocessed Man(5)GlcNAc(2), which is a target for cyanovirin-N, as well as unique, complex N-glycans containing Gal and Glc.
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Citation: J Biol Chem. 2008 Jun 27;283(26):18355-64. doi: 10.1074/jbc.M800725200. Epub 2008 Apr 16.Link to article on publisher's site
Magnelli, Paula; Cipollo, John F.; Ratner, Daniel M.; Cui, Jike; Kelleher, Daniel J.; Gilmore, Reid; Costello, Catherine E.; Robbins, Phillips W.; and Samuelson, John, "Unique Asn-linked oligosaccharides of the human pathogen Entamoeba histolytica" (2008). Biochemistry and Molecular Pharmacology Publications and Presentations. Paper 181.