title: Decrease in cell viability in an RMF, sigma(38), and OmpC triple mutant of Escherichia coli.
abstract: In a speG-disrupted Escherichia coli mutant, which cannot metabolize spermidine to acetylspermidine, addition of spermidine to the medium caused a decrease in cell viability at the late stationary phase of growth. There were parallel decreases in the levels of ribosome modulation factor (RMF), the sigma(38) subunit of RNA polymerase, and the outer membrane protein C (OmpC). To clarify that these three proteins are strongly involved in cell viability, the rmf, rpoS (encoding sigma(38)), and ompC genes were disrupted. Viability of the triple mutant decreased to less than 1% of normal cells. The triple mutant had a reduced cell viability compared to any combination of double mutants, which also had a reduced cell viability. The single rmf and rpoS, but not ompC, mutant only slightly reduced cell viability. The results indicate that cooperative functions of these three proteins are necessary for cell viability at the late stationary phase. The triple mutant had a reduced level of ribosomes and of intracellular cations.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, 263-8522, Chiba, Japan.
authors.forename: V
authors.initials: V
authors.lastname: Samuel Raj
authors.forename: Christine
authors.initials: C
authors.lastname: Füll
authors.forename: Madoka
authors.initials: M
authors.lastname: Yoshida
authors.forename: Kaori
authors.initials: K
authors.lastname: Sakata
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Akira
authors.initials: A
authors.lastname: Ishihama
authors.forename: Kazuei
authors.initials: K
authors.lastname: Igarashi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002455:Cell Division; D002499:Centrifugation, Density Gradient; D019281:Dimerization; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D009154:Mutation; D018272:Porins / Q000235:genetics / Q000502:physiology*; D012269:Ribosomal Proteins / Q000235:genetics / Q000502:physiology*; D012270:Ribosomes / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology*; D013095:Spermidine / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C113724:OmpC protein; D018272:Porins; D012269:Ribosomal Proteins; D012808:Sigma Factor; C063545:ribosome modulation factor, E coli; C069567:sigma factor KatF protein, Bacteria; D013095:Spermidine