title: (p)ppGpp-dependent and -independent pathways for salt tolerance in Escherichia coli.
abstract: Addition of some kinds of translation inhibitors targeting the ribosome such as kasugamycin to the culture medium as well as removal of a ribosome maturation factor or a ribosomal protein provides Escherichia coli cells with tolerance to high salt stress. Here, we found that another kind of translation inhibitor, serine hydroxamate (SHX), which induces amino acid starvation leading to (p)ppGpp production, also has a similar effect, but via a different pathway. Unlike kasugamycin, SHX was not effective in (p)ppGpp-null mutant cells. SHX and depletion of RsgA, a ribosome maturation factor, had an additive effect on salt tolerance, while kasugamycin or depletion of RsgA did not. These results indicate the presence of two distinct pathways, (p)ppGpp-dependent and -independent pathways, for salt tolerance of E. coli cell. Both pathways operate even in the absence of σ(S), an alternative sigma factor involved in the stationary phase or stress response. Hastened activation of the exocytoplasmic stress-specific sigma factor, σ(E), after salt shock was observed in the cells treated with SHX, as has been observed in the cells treated with a translation inhibitor or depleted of a ribosome maturation factor.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Takefusa
authors.initials: T
authors.lastname: Tarusawa
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Shion
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Simon
authors.initials: S
authors.lastname: Goto
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Ushida
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Muto
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan himeno@hirosaki-u.ac.jp.
authors.forename: Hyouta
authors.initials: H
authors.lastname: Himeno
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D055049:Salt Tolerance / Q000502:physiology*; D012694:Serine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D012808:Sigma Factor; C028002:serine hydroxamate; D012694:Serine; D020558:GTP Phosphohydrolases; C467318:RsgA protein, E coli
keywords: (p)ppGpp; Escherichia coli; osmoregulation; salt stress; serine hydroxamate; σE