title: Biochemistry of S-layers.
abstract: During evolution prokaryotes have developed different envelope structures exterior to the cell wall proper. Among these surface components are regularly arranged S-layers and capsules. The structural characterization and the detailed chemical analysis of these surface molecules is a prerequisite to understand their biosynthesis and functional role(s) at the molecular level. Of particular interest are the glycosylated S-layer proteins which belong to the first prokaryotic glycoproteins ever described. Their characterization was performed on strains belonging to the thermophilic Bacillaceae and included structural studies and experiments to learn about the pathways for the glycan biosynthesis of S-layer glycoproteins. As an example for non-glycosylated S-layer proteins those of Lactobacillus helveticus strains are described in detail. Recently, a novel type of bacterial glycoconjugate was observed in the cell envelope of the extremely halophilic archaeon Natronococcus occultus which consists of a glycosylated polyglutamyl polymer. Beside the conventional biochemical techniques for the analysis new sophisticated instrumental methods such as X-ray photoelectron spectroscopy and matrix-assisted laser desorption ionization or electrospray ionization mass spectrometry have been introduced for the analysis of the protein and glycan portions of these cell surface macromolecules.
authors.affiliation: Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Wien, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Messner
authors.forename: G
authors.initials: G
authors.lastname: Allmaier
authors.forename: C
authors.initials: C
authors.lastname: Schäffer
authors.forename: T
authors.initials: T
authors.lastname: Wugeditsch
authors.forename: S
authors.initials: S
authors.lastname: Lortal
authors.forename: H
authors.initials: H
authors.lastname: König
authors.forename: R
authors.initials: R
authors.lastname: Niemetz
authors.forename: M
authors.initials: M
authors.lastname: Dorner
mesh_terms: D001105:Archaea / Q000737:chemistry / Q000648:ultrastructure; D001406:Bacillaceae / Q000737:chemistry / Q000648:ultrastructure; D001419:Bacteria / Q000737:chemistry* / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry*; D005075:Biological Evolution; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000737:chemistry*; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure; D006001:Glycoconjugates / Q000737:chemistry*; D006031:Glycosylation; D013058:Mass Spectrometry / Q000379:methods; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011099:Polyglutamic Acid / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D006001:Glycoconjugates; D008562:Membrane Glycoproteins; D011134:Polysaccharides; C055764:S-layer proteins; D011099:Polyglutamic Acid