title: Structure and dynamics of pentaglycyl bridges in the cell walls of Staphylococcus aureus by 13C-15N REDOR NMR.
abstract: Whole cells and cell-wall fractions of Staphylococcusaureus have been labeled by various combinations of [1-13C]glycine, [15N]glycine, L--6-13C-lysine, L--6-15N-lysine, D--1-13C-alanine, and D--15N-alanine. The resulting materials have been examined using 13C and 15N solid-state, magic-angle spinning NMR techniques including cross-polarization, double cross-polarization, and rotational-echo double resonance. The results of these measurements indicate that the peptidoglycan glycyl bridges are complete (five units long) and form cross-links between three-quarters of all peptide stems. The pentaglycyl bridges are immobilized in lyophilized cell-wall fractions in a compact conformation with inter-residue spacings comparable to those of an alpha helix. The bridges have a similar compact conformation in intact whole cells, regardless of whether the cells have been lyophilized or were hydrated and frozen at -10 degrees C. The bridges are also in a time-averaged compact conformation in whole cells at 0 degrees C but with sizable structural fluctuations associated with local mobility. A small fraction of bridges are in extended-chain conformations.
authors.affiliation: Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: G
authors.initials: G
authors.lastname: Tong
authors.forename: Y
authors.initials: Y
authors.lastname: Pan
authors.forename: H
authors.initials: H
authors.lastname: Dong
authors.forename: R
authors.initials: R
authors.lastname: Pryor
authors.forename: G E
authors.initials: GE
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Schaefer
mesh_terms: D002473:Cell Wall / Q000737:chemistry; D003432:Cross-Linking Reagents; D005998:Glycine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010457:Peptidoglycan / Q000737:chemistry / Q000302:isolation & purification; D011487:Protein Conformation; D013211:Staphylococcus aureus / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D003432:Cross-Linking Reagents; D010457:Peptidoglycan; D005998:Glycine