title: The Cs sec mutants of Escherichia coli reflect the cold sensitivity of protein export itself.
abstract: We have found that temperature can have a striking effect upon protein export in Escherichia coli, suggesting that there is a cold-sensitive step in the protein export pathway. Cs mutations comprise the largest class of mutations affecting the membrane-localized Sec proteins SecD, SecE, SecF and SecY. Although some of these mutations could encode cold-labile proteins, this is unlikely to account for the Cs phenotype of most export mutants, as mutations which simply produce lower amounts of SecE protein have the same phenotype. Certain signal sequence mutations affecting maltose binding protein are also cold sensitive for export. These effects appear to arise by a specific interaction of cold with certain export defects. We believe that the Cs sec mutations are representative of a large class of conditional lethal mutations, whose conditional phenotype reflects an underlying thermal sensitivity of the process in which they are involved.
authors: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
authors: K J
authors: KJ
authors: Pogliano
authors: J
authors: J
authors: Beckwith
mesh_terms: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006868:Hydrolysis; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D021382:Protein Sorting Signals / Q000235:genetics
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D021382:Protein Sorting Signals; C499394:SecD protein, E coli; C489583:SecF protein, E coli; C461599:maltose transport system, E coli; C075767:secD protein, Bacteria; C075768:secF protein, Bacteria