title: Revisiting magnesium chelation by teichoic acid with phosphorus solid-state NMR and theoretical calculations.
abstract: Teichoic acids are essential components of the Gram-positive bacterial cell wall. One of their many functions is metal binding, a vital process for bacterial growth. With the combination of phosphorus-31 solid-state NMR spectroscopy and theoretical calculations using density functional theory (DFT), we have determined that the binding mode between teichoic acids and magnesium involves bidentate coordination by the phosphate groups of teichoic acid. Measurement of chemical shift anisotropy tensors gave a reduced anisotropy (delta) of 49.25 ppm and an asymmetry (eta) of 0.7. DFT calculations with diglycerol phosphate and triglycerol diphosphate model compounds were completed with Mg(2+) in anhydrous as well as partially hydrated bidentate and fully hydrated monodentate, bidentate, and bridging binding modes. (31)P CSA tensors were calculated from the energy-minimized model compounds using the combined DFT and GIAO methods, resulting in dramatically different tensor values for each binding mode. The anhydrous bidentate chelation mode was found to be a good approximation of the experimental data, an observation that alters the current monodentate paradigm for metal chelation by teichoic acids.
authors.affiliation: Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Room 208, Norman, Oklahoma 73019, USA.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Wickham
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Halye
authors.forename: Stepan
authors.initials: S
authors.lastname: Kashtanov
authors.forename: Jana
authors.initials: J
authors.lastname: Khandogin
authors.forename: Charles V
authors.initials: CV
authors.lastname: Rice
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002614:Chelating Agents / Q000737:chemistry*; D003198:Computer Simulation; D008274:Magnesium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010758:Phosphorus / Q000737:chemistry*; D012015:Reference Standards; D013682:Teichoic Acids / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D013682:Teichoic Acids; D010758:Phosphorus; D008274:Magnesium