title: New killing system controlled by two genes located immediately upstream of the mukB gene in Escherichia coli.
abstract: The nucleotide sequence was determined of the region upstream of the mukB gene of Escherichia coli. Two new genes were found, designated kicA and kicB (killing of cell); the gene order is kicB-kicA-mukB. Promoter activities were detected in the regions immediately upstream of kicB and kicA, but not in front of mukB. Gene disruption experiments revealed that the kicA disruptant was nonviable, but the kicB-disrupted mutant and the mutant lacking both the kicB and kicA genes were able to grow. When kicA disruptant cells bearing a temperature-sensitive replication plasmid carrying the kicA+ gene were grown at 30 degrees C and then transferred to 42 degrees C, the mutant cells gradually lost colony-forming ability, even in the presence of a mukB+ plasmid. Rates of protein synthesis, but not of RNA or DNA synthesis, fell dramatically during incubation at 42 degrees C. These results suggested that the kicB gene encodes a killing factor and the kicA gene codes for a protein that suppresses the killing function of the kicB gene product. It was also demonstrated that KicA and KicB can function as a post-segregational killing system, when the genes are transferred from the E. coli chromosome onto a plasmid.
authors.affiliation: Department of Molecular Cell Biology, Kumamoto University School of Medicine, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Feng
authors.forename: K
authors.initials: K
authors.lastname: Yamanaka
authors.forename: H
authors.initials: H
authors.lastname: Niki
authors.forename: T
authors.initials: T
authors.lastname: Ogura
authors.forename: S
authors.initials: S
authors.lastname: Hiraga
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D002455:Cell Division; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D005804:Genes, Lethal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000096:biosynthesis; D012097:Repressor Proteins / Q000096:biosynthesis; D014161:Transduction, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; C087115:mukE protein, E coli; C087116:mukF protein, E coli