Synapsis and the formation of paranemic joints by E. coli RecA protein

Marco Bianchi, Chanchal Dasgupta, Charles M. Radding

Research output: Contribution to journalArticlepeer-review


E. coli RecA protein promotes the homologous pairing of a single strand with duplex DNA even when certain features of the substrates, such as circularity, prohibit the true intertwining of the newly paired strands. The formation of such nonintertwined or paranemic joints does not require superhelicity, and indeed can occur with relaxed closed circular DNA. E. coli topoisomerase I can intertwine the incoming single strand in the paranemic joint with its complement, thereby topologically linking single-stranded DNA to all of the duplex molecules in the reaction mixture. The efficiency of formation of paranemic joints, the time course, and estimates of their length, all suggest that they represent true synaptic intermediates in the pairing reaction promoted by RecA protein.

Original languageEnglish
Pages (from-to)931-939
Number of pages9
Issue number3
Publication statusPublished - 1983

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology


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