title: Diversity in prokaryotic glycosylation: an archaeal-derived N-linked glycan contains legionaminic acid.
abstract: VP4, the major structural protein of the haloarchaeal pleomorphic virus, HRPV-1, is glycosylated. To define the glycan structure attached to this protein, oligosaccharides released by β-elimination were analysed by mass spectrometry and nuclear magnetic resonance spectroscopy. Such analyses showed that the major VP4-derived glycan is a pentasaccharide comprising glucose, glucuronic acid, mannose, sulphated glucuronic acid and a terminal 5-N-formyl-legionaminic acid residue. This is the first observation of legionaminic acid, a sialic acid-like sugar, in an archaeal-derived glycan structure. The importance of this residue for viral infection was demonstrated upon incubation with N-acetylneuraminic acid, a similar monosaccharide. Such treatment reduced progeny virus production by half 4 h post infection. LC-ESI/MS analysis confirmed the presence of pentasaccharide precursors on two different VP4-derived peptides bearing the N-glycosylation signal, NTT. The same sites modified by the native host, Halorubrum sp. strain PV6, were also recognized by the Haloferax volcanii N-glycosylation apparatus, as determined by LC-ESI/MS of heterologously expressed VP4. Here, however, the N-linked pentasaccharide was the same as shown to decorate the S-layer glycoprotein in this species. Hence, N-glycosylation of the haloarchaeal viral protein, VP4, is host-specific. These results thus present additional examples of archaeal N-glycosylation diversity and show the ability of Archaea to modify heterologously expressed proteins.
authors.affiliation: Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 84105, Israel.
authors.forename: Lina
authors.initials: L
authors.lastname: Kandiba
authors.forename: Olli
authors.initials: O
authors.lastname: Aitio
authors.forename: Jari
authors.initials: J
authors.lastname: Helin
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Guan
authors.forename: Perttu
authors.initials: P
authors.lastname: Permi
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Bamford
authors.forename: Jerry
authors.initials: J
authors.lastname: Eichler
authors.forename: Elina
authors.initials: E
authors.lastname: Roine
mesh_terms: D000595:Amino Acid Sequence; D023641:Archaeal Viruses / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D019622:Haloferax volcanii / Q000378:metabolism* / Q000821:virology; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism*; D012794:Sialic Acids / Q000032:analysis / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C110570:5,7-diacetamido-8-O-acetyl-3,5,7,9-tetradeoxy-glycero-talo-nonulosonic acid; D011134:Polysaccharides; D012794:Sialic Acids; D014764:Viral Proteins