title: Identification and characterization of the unique N-linked glycan common to the flagellins and S-layer glycoprotein of Methanococcus voltae.
abstract: The flagellum of Methanococcus voltae is composed of four structural flagellin proteins FlaA, FlaB1, FlaB2, and FlaB3. These proteins possess a total of 15 potential N-linked sequons (NX(S/T)) and show a mass shift on an SDS-polyacrylamide gel indicating significant post-translational modification. We describe here the structural characterization of the flagellin glycan from M. voltae using mass spectrometry to examine the proteolytic digests of the flagellin proteins in combination with NMR analysis of the purified glycan using a sensitive, cryogenically cooled probe. Nano-liquid chromatography-tandem mass spectrometry analysis of the proteolytic digests of the flagellin proteins revealed that they are post-translationally modified with a novel N-linked trisaccharide of mass 779 Da that is composed of three sugar residues with masses of 318, 258, and 203 Da, respectively. In every instance the glycan is attached to the peptide through the asparagine residue of a typical N-linked sequon. The glycan modification has been observed on 14 of the 15 sequon sites present on the four flagellin structural proteins. The novel glycan structure elucidated by NMR analysis was shown to be a trisaccharide composed of beta-ManpNAcA6Thr-(1-4)-beta-Glc-pNAc3NAcA-(1-3)-beta-GlcpNAc linked to Asn. In addition, the same trisaccharide was identified on a tryptic peptide of the S-layer protein from this organism implicating a common N-linked glycosylation pathway.
authors.affiliation: Institute for Biological Sciences, National Research Council, Ottawa, Ontario K1A OR6, Canada.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Voisin
authors.forename: R Scott
authors.initials: RS
authors.lastname: Houliston
authors.forename: John
authors.initials: J
authors.lastname: Kelly
authors.forename: Jean-Robert
authors.initials: JR
authors.lastname: Brisson
authors.forename: David
authors.initials: D
authors.lastname: Watson
authors.forename: Sonia L
authors.initials: SL
authors.lastname: Bardy
authors.forename: Ken F
authors.initials: KF
authors.lastname: Jarrell
authors.forename: Susan M
authors.initials: SM
authors.lastname: Logan
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry; D001665:Binding Sites; D015153:Blotting, Western; D002241:Carbohydrates / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005408:Flagellin / Q000737:chemistry; D006031:Glycosylation; D006859:Hydrogen / Q000737:chemistry; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D017017:Methanococcus / Q000378:metabolism*; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D021241:Spectrometry, Mass, Electrospray Ionization; D014357:Trypsin / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D007477:Ions; D011134:Polysaccharides; D011506:Proteins; D005408:Flagellin; D001216:Asparagine; D006859:Hydrogen; D014357:Trypsin