title: Role of the RuvAB protein in avoiding spontaneous formation of deletion mutations in the Escherichia coli K-12 endogenous tonB gene.
abstract: The endogenous tonB gene of Escherichia coli was used as a target for spontaneous deletion mutations which were isolated from ruvAB-, recG-, and ruvC- cells. The rates of tonB mutation were essentially the same in ruv+, ruvAB-, recG-, and ruvC- cells. We analyzed tonB mutants by sequencing. In the ruv+, recG-, and ruvC- strains, the spectra were different from those obtained from the ruvAB- cells, where deletions dominated followed by IS insertions, base substitutions, and frameshifts, in that order. We then analyzed the tonB-trp large deletion, due to simultaneous mutations of the trp operon, and found that the frequency in ruvAB- was higher than those in ruv+, recG-, and ruvC- cells. To characterize deletion formation further, we analyzed all the tonB mutants from one colicin plate. Seven deletions were identified at five sites from the 45 tonB mutants of ruv+ cells and 24 deletions at 11 sites from the 43 tonB mutants of ruvAB- cells. Thus, the ruvAB- strain is a deletion mutator. We discuss the role of RuvAB in avoiding deletions.
authors.affiliation: Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Mashimo
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masakado
authors.initials: M
authors.lastname: Kawata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwasaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D003087:Colicins / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004706:Endodeoxyribonucleases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D008565:Membrane Proteins / Q000235:genetics*; D008957:Models, Genetic; D016296:Mutagenesis; D009154:Mutation; D010957:Plasmids / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003087:Colicins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C061260:RuvB protein, Bacteria; C069806:ruvC protein, E coli; C057616:tonB protein, Bacteria; C071446:RecG protein, E coli; D004706:Endodeoxyribonucleases; C071059:Holliday junction DNA helicase, E coli; D004265:DNA Helicases