title: The S-Layer Protein of the Anammox BacteriumKuenenia stuttgartiensisIs HeavilyO-Glycosylated.
abstract: Anaerobic ammonium oxidation (anammox) bacteria are a distinct group of Planctomycetes that are characterized by their unique ability to perform anammox with nitrite to dinitrogen gas in a specialized organelle. The cell of anammox bacteria comprises three membrane-bound compartments and is surrounded by a two-dimensional crystalline S-layer representing the direct interaction zone of anammox bacteria with the environment. Previous results from studies with the model anammox organismKuenenia stuttgartiensissuggested that the protein monomers building the S-layer lattice are glycosylated. In the present study, we focussed on the characterization of the S-layer protein glycosylation in order to increase our knowledge on the cell surface characteristics of anammox bacteria. Mass spectrometry (MS) analysis showed anO-glycan attached to 13 sites distributed over the entire 1591-amino acid S-layer protein. This glycan is composed of six monosaccharide residues, of which five areN-acetylhexosamine (HexNAc) residues. Four of these HexNAc residues have been identified as GalNAc. The sixth monosaccharide in the glycan is a putative dimethylated deoxyhexose. Two of the HexNAc residues were also found to contain a methyl group, thereby leading to an extensive degree of methylation of the glycan. This study presents the first characterization of a glycoprotein in a planctomycete and shows that the S-layer protein Kustd1514 ofK. stuttgartiensisis heavily glycosylated with anO-linked oligosaccharide which is additionally modified by methylation. S-layer glycosylation clearly contributes to the diversification of theK. stuttgartiensiscell surface and can be expected to influence the interaction of the bacterium with other cells or abiotic surfaces.
authors.affiliation: Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Netherlands.
authors.forename: Muriel C F
authors.initials: MC
authors.lastname: van Teeseling
authors.affiliation: Division of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Maresch
authors.affiliation: NanoGlycobiology Unit, Department of NanoBiotechnology, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Cornelia B
authors.initials: CB
authors.lastname: Rath
authors.affiliation: Division of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Figl
authors.affiliation: Division of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
authors.affiliation: Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Netherlands.
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
authors.affiliation: NanoGlycobiology Unit, Department of NanoBiotechnology, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Messner
authors.affiliation: NanoGlycobiology Unit, Department of NanoBiotechnology, University of Natural Resources and Life Sciences Vienna, Austria.
authors.forename: Christina
authors.initials: C
authors.lastname: Schäffer
authors.affiliation: Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Netherlands.
authors.forename: Laura
authors.initials: L
authors.lastname: van Niftrik
keywords: Kuenenia stuttgartiensis; O-glycan; S-layer; anammox bacteria; glycoprotein; methylation