title: Structure of peptidoglycan from Thermus thermophilus HB8.
abstract: The composition and structure of peptidoglycan (murein) extracted from the extreme thermophilic eubacterium Thermus thermophilus HB8 are presented. The structure of 29 muropeptides, accounting for more than 85% of total murein, is reported. The basic monomeric subunit consists of N-acetylglucosamine-N-acetylmuramic acid-L-Ala-D-Glu-L-Orn-D-Ala-D-Ala, acylated at the delta-NH2 group of Orn by a Gly-Gly dipeptide. In a significant proportion (about 23%) of total muropeptides, the N-terminal Gly is substituted by a residue of phenylacetic acid. This is the first time phenylacetic acid is described as a component of bacterial murein. Possible implications for murein physiology and biosynthesis are discussed. Murein cross-linking is mediated by D-Ala-Gly-Gly peptide cross-bridges. Glycan chains are apparently terminated by (1-->6) anhydro N-acetylmuramic acid residues. Neither reducing sugars nor murein-bound macromolecules were detected. Murein from T. thermophilus presents an intermediate complexity between those of gram-positive and gram-negative organisms. The murein composition and peptide cross-bridges of T. thermophilus are typical for a gram-positive bacterium. However, the murein content, degree of cross-linkage, and glycan chain length for T. thermophilus are closer to those for gram-negative organisms and could explain the gram-negative character of Thermus spp.
authors.affiliation: Centro de Biología Molecular Severo Ochoa Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, Facultad de Ciencias, Campus de Cantoblanco, Madrid, Spain.
authors.forename: J C
authors.initials: JC
authors.lastname: Quintela
authors.forename: E
authors.initials: E
authors.lastname: Pittenauer
authors.forename: G
authors.initials: G
authors.lastname: Allmaier
authors.forename: V
authors.initials: V
authors.lastname: Arán
authors.forename: M A
authors.initials: MA
authors.lastname: de Pedro
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000737:chemistry*; D002473:Cell Wall / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009112:Muramic Acids / Q000032:analysis; D009952:Ornithine / Q000032:analysis; D010455:Peptides / Q000737:chemistry*; D010457:Peptidoglycan / Q000737:chemistry*; D010648:Phenylacetates / Q000032:analysis; D013237:Stereoisomerism; D016963:Thermus thermophilus / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D009112:Muramic Acids; D010455:Peptides; D010457:Peptidoglycan; D010648:Phenylacetates; C031651:N-acetylmuramic acid; D009952:Ornithine; C025136:phenylacetic acid; D000117:Acetylglucosamine