New topoisomerase essential for chromosome segregation in E. coli

Cell. 1990 Oct 19;63(2):393-404. doi: 10.1016/0092-8674(90)90172-b.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus subtilis / enzymology
  • Bacillus subtilis / genetics
  • Base Sequence
  • Chromosomes, Bacterial / physiology*
  • DNA Topoisomerase IV
  • DNA Topoisomerases, Type I / genetics*
  • DNA Topoisomerases, Type II / genetics
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Genes, Bacterial*
  • Macromolecular Substances
  • Molecular Sequence Data
  • Mutation
  • Plasmids
  • Restriction Mapping
  • Sequence Homology, Nucleic Acid


  • Macromolecular Substances
  • DNA Topoisomerase IV
  • DNA Topoisomerases, Type I
  • DNA Topoisomerases, Type II

Associated data

  • GENBANK/M37832
  • GENBANK/M37833
  • GENBANK/M58408
  • GENBANK/M58409