title: Characterization of peptidoglycan in fem-deletion mutants of methicillin-resistant Staphylococcus aureus by solid-state NMR.
abstract: Compositional analysis of the peptidoglycan (PG) of a wild-type methicillin-resistant Staphylococcus aureus and its fem-deletion mutants has been performed on whole cells and cell walls using stable-isotope labeling and rotational-echo double-resonance NMR. The labels included [1-(13)C,(15)N]glycine and l-[epsilon-(15)N]lysine (for a direct measure of the number of glycyl residues in the bridging segment), [1-(13)C]glycine and l-[epsilon-(15)N]lysine (concentration of bridge links), and d-[1-(13)C]alanine and [(15)N]glycine (concentrations of cross-links and wall teichoic acids). The bridging segment length changed from 5.0 glycyl residues (wild-type strain) to 2.5 +/- 0.1 (FemB) with modest changes in cross-link and bridge-link concentrations. This accurate in situ measurement for the FemB mutant indicates a heterogeneous PG structure with 25% monoglycyl and 75% triglycyl bridges. When the bridging segment was reduced to a single glycyl residue 1.0 +/- 0.1 (FemA), the level of cross-linking decreased by more than 20%, resulting in a high concentration of open N-terminal glycyl segments.
authors.affiliation: Department of Chemistry, Washington University, One Brookings Drive, St. Louis, Missouri 63130, USA.
authors.forename: Shasad
authors.initials: S
authors.lastname: Sharif
authors.forename: Sung Joon
authors.initials: SJ
authors.lastname: Kim
authors.forename: Harald
authors.initials: H
authors.lastname: Labischinski
authors.forename: Jacob
authors.initials: J
authors.lastname: Schaefer
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000737:chemistry* / Q000235:genetics; D009154:Mutation; D009587:Nitrogen Isotopes; D010457:Peptidoglycan / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D002247:Carbon Isotopes; C102928:FemB protein, Staphylococcus epidermidis; D009587:Nitrogen Isotopes; D010457:Peptidoglycan