Ultrastructural Study of Salmonella typhimurium Treated with Membrane-Active Agents: Specific Reaction of Dansylchloride with Cell Envelope Components

Peter R. G. Schindler, Michael Teuber
1978 Journal of Bacteriology  
Amino groups of cell envelope proteins, lipids, and lipopolysaccharides cannot be labeled in intact cells of Salmonella typhimurium G 30 by using 5-diznethylaminonaphthalene-l-sulfonylchloride incorporated in lecithin-cholesterol vesicles. However, application of membrane-interacting agents like tris(hydroxymethyl)aminomethane (Tris)-hydrochloride, ethylenediaminetetraacetate (Na salt) (EDTA), divalent cations, and sublethal doses of the cationic antibacterial agents polymyxin B and
more » ... n B and chlorhexidine induced specific fluorescent labeling of envelope proteins and lipids but not of cytoplasmic compounds, with the exception of a soluble protein with a molecular weight of 46,000 in sodium dodecyl sulfatepolyacrylamide gel electrophoresis. Treatment with Tris-hydrochloride buffer produced labeling of the heat-modifiable protein B/B+ and of proteins with molecular weights of 26,000, 22,000, and below 17,000. A combination of Trishydrochloride and EDTA induced additional dansylation of the major protein A and of proteins of molecular weights 80,000, 60,000, and 44,000. Polymyxin B and chlorhexidine caused similar labeling patterns. In every case, except with divalent cation treatment, protein B/B+ was the most prominently labeled species. Phosphatidylethanolamine was dansylated up to 30%. Lipopolysaccharide was not reactive under any condition or treatment. In addition, the peptidoglycan-bound lipoprotein did not react with dansylchloride in either intact or Tris-hydrochloride-treated cells. The results are discussed with regard to a possible localization of labeled and unlabeled compounds of the cell envelope on the basis of a model placing cell envelope amino groups into ion-ion interactions with anionic components of other envelope compounds like phosphate and carboxyl groups. Trishydrochlorideethylenediaminetetraacetate (Na salt) (EDTA), which is known to release the acidic compound LPS from the envelope (17), and the cationic antibiotics polymyxin B and chlorhexidine, which complex with LPS (2) and acidic phospholipids (18, 36) , were also investigated. 198 on May 7, 2020 by guest
doi:10.1128/jb.135.1.198-206.1978 fatcat:ksealtyqavacfcjazoaofp6sqm