title: The aqueous solution structure of a lipoteichoic acid from Streptococcus pneumoniae strain R6 containing 2,4-diamino-2,4,6-trideoxy-galactose: evidence for conformational mobility of the galactopyranose ring.
abstract: The 2D-NOESY spectra for the per-N-acetylated and the native lipoteichoic acid (LTA) oligomer from Streptococcus pneumoniae strain R6 clearly indicate a difference in conformation of the 2,4,6-trideoxy-galactopyranose ring. Whereas the 2,4-N-acetylated Gal24N adopts the usual 4C1 chair conformation, the native 2-N-acetyl-4-amino Gal24N exhibits conformational mobility with comparable populations in the 4C1 chair and 5S1 skew conformations, as determined using MD simulation for the partial trisaccharide Me-beta-D-Glc6P-(1-->3)-alpha-D-Gal24N-[6-PC]-(1-->4)-alpha- D-galNAc and from the intra-ring NOE effects. 31P-NMR spectra point to a strong electrostatic or hydrogen-bonding interaction between the free 4-NH2 group on the Gal24N and the negatively charged diester phosphate group between adjacent pentasaccharide repeating-units [Ribitol-(5-->6)-beta-D-Glc6P]. Molecular modelling and MD simulation experiments confirmed that such an interaction was feasible with the Gal24N galactopyranose ring in the inverted B1.4 or skew 5S1 conformation.
authors.affiliation: Institut für Physiologische Chemie der Universität Bonn, Germany.
authors.forename: R A
authors.initials: RA
authors.lastname: Klein
authors.forename: R
authors.initials: R
authors.lastname: Hartmann
authors.forename: H
authors.initials: H
authors.lastname: Egge
authors.forename: T
authors.initials: T
authors.lastname: Behr
authors.forename: W
authors.initials: W
authors.lastname: Fischer
mesh_terms: D000116:Acetylgalactosamine / Q000032:analysis; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004075:Diglycerides / Q000032:analysis; D005690:Galactose / Q000031:analogs & derivatives* / Q000737:chemistry; D005947:Glucose / Q000032:analysis; D008070:Lipopolysaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D010710:Phosphates / Q000032:analysis; D010767:Phosphorylcholine / Q000032:analysis; D012091:Repetitive Sequences, Nucleic Acid; D012255:Ribitol / Q000032:analysis; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D013682:Teichoic Acids / Q000737:chemistry*; D014312:Trisaccharides / Q000737:chemistry
chemical_list: C098834:2,4-diamino-2,4,6-trideoxygalactose; D004075:Diglycerides; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D010710:Phosphates; D013682:Teichoic Acids; D014312:Trisaccharides; D010767:Phosphorylcholine; D012255:Ribitol; C009900:lipoteichoic acid; D005947:Glucose; D000116:Acetylgalactosamine; D005690:Galactose