title: New topoisomerase essential for chromosome segregation in E. coli.
abstract: The nucleotide sequence of the parC gene essential for chromosome partition in E. coli was determined. The deduced amino acid sequence was homologous to that of the A subunit of gyrase. We found another new gene coding for about 70 kd protein. The gene was sequenced, and the deduced amino acid sequence revealed that the gene product was homologous to the gyrase B subunit. Mutants of this gene were isolated and showed the typical Par phenotype at nonpermissive temperature; thus the gene was named parE. Enhanced relaxation activity of supercoiled plasmid molecules was detected in the combined crude cell lysates prepared from the ParC and ParE overproducers. A topA mutation defective in topoisomerase I could be compensated by increasing both the parC and the parE gene dosage. It is suggested that the parC and parE genes code for the subunits of a new topoisomerase, named topo IV.
authors.affiliation: Department of Bacteriology, National Institute of Health of Japan, Tokyo.
authors.forename: J
authors.initials: J
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Nishimura
authors.forename: R
authors.initials: R
authors.lastname: Imamura
authors.forename: H
authors.initials: H
authors.lastname: Niki
authors.forename: S
authors.initials: S
authors.lastname: Hiraga
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000502:physiology*; D027101:DNA Topoisomerase IV; D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
chemical_list: D046911:Macromolecular Substances; D027101:DNA Topoisomerase IV; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II