Investigating direct interaction between Escherichia coli topoisomerase I and RecA

Gene. 2016 Jul 1;585(1):65-70. doi: 10.1016/j.gene.2016.03.013. Epub 2016 Mar 19.


Protein-protein interactions are of special importance in cellular processes, including replication, transcription, recombination, and repair. Escherichia coli topoisomerase I (EcTOP1) is primarily involved in the relaxation of negative DNA supercoiling. E. coli RecA, the key protein for homologous recombination and SOS DNA-damage response, has been shown to stimulate the relaxation activity of EcTOP1. The evidence for their direct protein-protein interaction has not been previously established. We report here the direct physical interaction between E. coli RecA and topoisomerase I. We demonstrated the RecA-topoisomerase I interaction via pull-down assays, and surface plasmon resonance measurements. Molecular docking supports the observation that the interaction involves the topoisomerase I N-terminal domains that form the active site. Our results from pull-down assays showed that ATP, although not required, enhances the RecA-EcTOP1 interaction. We propose that E. coli RecA physically interacts with topoisomerase I to modulate the chromosomal DNA supercoiling.

Keywords: DNA topoisomerase I; Molecular docking; Protein–protein interactions; Pull-down assay; RecA; SPR.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Catalytic Domain / genetics
  • DNA Topoisomerases, Type I / genetics*
  • DNA, Superhelical / genetics*
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Homologous Recombination / genetics
  • Molecular Docking Simulation
  • Rec A Recombinases / genetics*
  • SOS Response, Genetics / genetics
  • Surface Plasmon Resonance


  • DNA, Superhelical
  • Rec A Recombinases
  • DNA Topoisomerases, Type I