title: The cell wall polymer of the extremely halophilic archaeon Natronococcus occultus.
abstract: The cell wall polymer of Natronococcus occultus (DSM 3396) consists of L-glutamate, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, D-galacturonic acid, D-glucuronic acid and D-glucose in a molar ratio of 5:7:1:8:0.5:0.3. Partial acid hydrolysis of the cell wall polymer produced soluble fragments that could be separated by HPLC. A gamma-glutamyl dipeptide was isolated. In the intact cell wall polymer, the glutamate residues form a poly-(gamma-glutamine) chain with a length of about 60 monomers, which corresponds to a relative molecular mass of approximately 7700 Da. Two other soluble dimeric fragments, composed of glutamate and either glucosamine or galactosamine in a molar ratio of 1:1, were purified from the hydrolysate, suggesting the presence of two different oligosaccharides linked to the poly-(gamma-glutamine) chain of the intact polymer. The analysis of additional fragments, which were composed of an amino sugar and galacturonic acid or glucose indicated that one oligosaccharide consisted of a glucosamine pentamer in an alpha-1,3 linkage at the reducing end and an oligomer with at least five beta-1,4-linked galacturonic acid residues at the non-reducing end. The second oligosaccharide was comprised of a galactosamine dimer in a beta-1,3 linkage at the reducing end and a maltose unit at the non-reducing end. Both oligosaccharides were linked to the alpha-amide group of the glutamine residues of the poly-(gamma-glutamine) chain. The whole cell wall polymer, which represents a novel type of natural glycoconjugate, has a relative molecular mass of 54 kDa.
authors.affiliation: Angewandte Mikrobiologie, Universität Ulm, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Niemetz
authors.forename: U
authors.initials: U
authors.lastname: Kärcher
authors.forename: O
authors.initials: O
authors.lastname: Kandler
authors.forename: B J
authors.initials: BJ
authors.lastname: Tindall
authors.forename: H
authors.initials: H
authors.lastname: König
mesh_terms: D000595:Amino Acid Sequence; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D006001:Glycoconjugates / Q000032:analysis / Q000737:chemistry*; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000032:analysis; D019634:Natronococcus / Q000737:chemistry*; D009844:Oligosaccharides / Q000032:analysis / Q000737:chemistry*; D010455:Peptides / Q000032:analysis* / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D006001:Glycoconjugates; D009005:Monosaccharides; D009844:Oligosaccharides; D010455:Peptides; C097188:polyglutamine