title: R factor proteins synthesized in Escherichia coli minicells: membrane-associated R factor proteins.
abstract: R factor proteins are synthesized in R factor-containing Escherichia coli minicells. Half of this protein remained associated with the minicell membrane upon lysis of the minicells. Over 90% of the membrane-associated protein was extracted by sodium lauryl sarcosinate, suggesting a location of these proteins in the inner membrane. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these membrane preparations demonstrated the presence of multiple peptides, including a prominent band with a molecular weight of 28,000 to 30,000. A polypeptide of similar size was seen in membrane preparations from minicells harboring R factors from five different compatibility types. This major R factor membrane peptide was seen with R factors repressed or derepressed for pilus synthesis, with and without antibiotic resistances. It was associated with R factor deoxyribonucleic acid in membrane-deoxyribonucleic acid complexes. Its possible role in R factor replication and/or transfer is being investigated.
mesh_terms: D001345:Autoradiography; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002250:Carbon Radioisotopes; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D005111:Extrachromosomal Inheritance; D008715:Methionine; D008970:Molecular Weight; D013462:Sulfur Radioisotopes; D014316:Tritium
chemical_list: D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D013462:Sulfur Radioisotopes; D014316:Tritium; D008715:Methionine