title: Protein composition of Rhodopseudomonas sphaeroides outer membrane.
abstract: The outer membrane polypeptide profile of Rhodopseudmonas sphaeroides was characterized. Solubilization of the outer membrane at 75 or 100 degrees C as opposed to room temperature resulted in the dissociation of 75-, 72-, and 68-kilodalton (kdal) polypeptide aggregates into 29-, 26.5-, and 21.5-kdal polypeptides, respectively, and a shared 47-kdal subunit. Similarly, an 88.5-kdal polypeptide dissociates into a 45-kdal monomeric form, and the electrophoretic mobility of a 58.5-kdal polypeptide was altered to 83 kdal. Lysozyme treatment of outer membrane fractions altered the 21.5-kdal polypeptide mobility to 23 kdal. The presence of lipid in both the 47-kdal polypeptide and an 8- to 10-kdal polypeptide was demonstrated by lipid staining and [14C]acetate incorporation. The lipid component of the 47-kdal polypeptide was neither lipopolysaccharide nor phospholipid. The 8- to 10-kdal polypeptide may be the equivalent of the Braun lipoprotein. Outer membrane fractions isolated from R. sphaeroides-specific phage RS1-resistant mutants were deficient in several of the high-molecular-weight aggregates involving the 47-kdal polypeptide.
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis*; D001435:Bacteriophages / Q000254:growth & development; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D008055:Lipids / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis*; D008970:Molecular Weight; D009113:Muramidase / Q000494:pharmacology; D009154:Mutation; D010455:Peptides / Q000032:analysis; D012242:Rhodobacter sphaeroides / Q000032:analysis*
chemical_list: D001426:Bacterial Proteins; D008055:Lipids; D008565:Membrane Proteins; D010455:Peptides; D009113:Muramidase