title: AglR is required for addition of the final mannose residue of the N-linked glycan decorating the Haloferax volcanii S-layer glycoprotein.
abstract: BACKGROUND
  Recent studies of Haloferax volcanii have begun to elucidate the steps of N-glycosylation in Archaea, where this universal post-translational modification remains poorly described. In Hfx. volcanii, a series of Agl proteins catalyzes the assembly and attachment of a N-linked pentasaccharide to the S-layer glycoprotein. Although roles have been assigned to the majority of Agl proteins, others await description. In the following, the contribution of AglR to N-glycosylation was addressed.
  
  
  METHODS
  A combination of bioinformatics, gene deletion, mass spectrometry and metabolic radiolabeling served to show a role for AglR in archaeal N-glycosylation at both the dolichol phosphate and reporter glycoprotein levels.
  
  
  RESULTS
  The modified behavior of the S-layer glycoprotein isolated from cells lacking AglR points to an involvement of this protein in N-glycosylation. In cells lacking AglR, glycan-charged dolichol phosphate, including mannose-charged dolichol phosphate, accumulates. At the same time, the S-layer glycoprotein does not incorporate mannose, the final subunit of the N-linked pentasaccharide decorating this protein. AglR is a homologue of Wzx proteins, annotated as flippases responsible for delivering lipid-linked O-antigen precursor oligosaccharides across the bacterial plasma membrane during lipopolysaccharide biogenesis.
  
  
  CONCLUSIONS
  The effects resulting from aglR deletion are consistent with AglR interacting with dolichol phosphate-mannose, possibly acting as a dolichol phosphate-mannose flippase or contributing to such activity.
  
  
  CONCLUSIONS
  Little is known of how lipid-linked oligosaccharides are translocated across membrane during N-glycosylation. The possibility of Hfx. volcanii AglR mediating or contributing to flippase activity could help address this situation.
authors: Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 84105, Israel.
authors: Lina
authors: L
authors: Kaminski
authors: Ziqiang
authors: Z
authors: Guan
authors: Mehtap
authors: M
authors: Abu-Qarn
authors: Zvia
authors: Z
authors: Konrad
authors: Jerry
authors: J
authors: Eichler
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002853:Chromatography, Liquid; D006031:Glycosylation; D019622:Haloferax volcanii / Q000235:genetics / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D030781:Organisms, Genetically Modified; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000235:genetics; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D019843:Archaeal Proteins; D008562:Membrane Glycoproteins; D011134:Polysaccharides; C055764:S-layer proteins; D008358:Mannose