title: A (2)H solid-state NMR study of the effect of antimicrobial agents on intact Escherichia coli without mutating.
abstract: Solid-state nuclear magnetic resonance (NMR) is a useful tool to probe the organization and dynamics of phospholipids in bilayers. The interactions of molecules with membranes are usually studied with model systems; however, the complex composition of biological membranes motivates such investigations on intact cells. We have thus developed a protocol to deuterate membrane phospholipids in Escherichia coli without mutating to facilitate (2)H solid-state NMR studies on intact bacteria. By exploiting the natural lipid biosynthesis pathway and using perdeuterated palmitic acid, our results show that 76% deuteration of the phospholipid fatty acid chains was attained. To verify the responsiveness of these membrane-deuterated E. coli, the effect of known antimicrobial agents was studied. (2)H solid-state NMR spectra combined to spectral moment analysis support the insertion of the antibiotic polymyxin B lipid tail in the bacterial membrane. The use of membrane-deuterated bacteria was shown to be important in cases where antibiotic action of molecules relies on the interaction with lipopolysaccharides. This is the case of fullerenol nanoparticles which showed a different effect on intact cells when compared to dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol membranes. Our results also suggest that membrane rigidification could play a role in the biocide activity of the detergent cetyltrimethyammonium chloride. Finally, the deuterated E. coli were used to verify the potential antibacterial effect of a marennine-like pigment produced by marine microalgae. We were able to detect a different perturbation of the bacteria membranes by intra- and extracellular forms of the pigment, thus providing valuable information on their action mechanism and suggesting structural differences.
authors.affiliation: Department of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montréal, Québec, Canada H3C 3P8.
authors.forename: Catherine
authors.initials: C
authors.lastname: Tardy-Laporte
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Arnold
authors.forename: Bertrand
authors.initials: B
authors.lastname: Genard
authors.forename: Romain
authors.initials: R
authors.lastname: Gastineau
authors.forename: Michèle
authors.initials: M
authors.lastname: Morançais
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Mouget
authors.forename: Réjean
authors.initials: R
authors.lastname: Tremblay
authors.forename: Isabelle
authors.initials: I
authors.lastname: Marcotte
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D003902:Detergents / Q000737:chemistry; D017377:Diatoms; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D037741:Fullerenes / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008826:Microbial Sensitivity Tests; D008956:Models, Chemical; D015233:Models, Statistical; D053758:Nanoparticles / Q000737:chemistry; D019308:Palmitic Acid / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D013696:Temperature
chemical_list: D000890:Anti-Infective Agents; D003902:Detergents; D037741:Fullerenes; D008051:Lipid Bilayers; D008055:Lipids; D010743:Phospholipids; C108127:fullerenol; D019308:Palmitic Acid