title: Characterization of the cell wall and outer membrane of Rhodopseudomonas capsulata.
abstract: Sucrose density gradient centrifugation of cell envelopes of chemotrophically grown cells of Rhodopseudomonas capsulata St. Louis (= ATCC 23782) resulted in the separation of a cytoplasmic membrane from a cell wall fraction (buoyant densities, 1.139 and 1.215 g/cm3, respectively). The cell wall fractions (untreated or Triton extracted) contained peptidoglycan- and lipopolysaccharide-specific components. Their neutral sugar content, mainly rhamnose and galactose, was high (250 and 100 micrograms/mg [dry weight] of material) due to a non-lipopolysaccharide polymer. The fatty acid content was low (less than or equal to 60 micrograms/mg [dry weight] of material), and half of it was contributed by lipopolysaccharide (3-OH-C10:0, C12:1, and 3-oxo-C14:0). The predominant other fatty acid was C18:1. An outer membrane fraction, obtained by lysozyme treatment of the Triton-extracted cell wall, showed essentially the same chemical composition except for almost complete removal of peptidoglycan. Saline extraction (0.9% NaCl, 37 degrees C, 2 h) removed a lipopolysaccharide-protein(-phospholipid?) complex from whole cells of R. capsulata St. Louis. The polypeptide patterns of the cell wall and outer membrane as revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis comprised 20 to 25 different polypeptides (most of them very faint) and were dominated by a single, heat-modifiable major protein (Mr 69,000 after solubilization below 60 degrees C; Mr 33,000 at temperatures above 70 degrees C).
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002458:Cell Fractionation; D002462:Cell Membrane / Q000648:ultrastructure; D002473:Cell Wall / Q000648:ultrastructure; D002499:Centrifugation, Density Gradient / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D008563:Membrane Lipids / Q000302:isolation & purification; D008565:Membrane Proteins / Q000302:isolation & purification; D008970:Molecular Weight; D010457:Peptidoglycan / Q000302:isolation & purification; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification; D012241:Rhodopseudomonas / Q000648:ultrastructure*
chemical_list: D002241:Carbohydrates; D008563:Membrane Lipids; D008565:Membrane Proteins; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial