Stable DNA heteroduplex formation catalyzed by the Escherichia coli RecA protein in the absence of ATP hydrolysis

Joseph P. Menetski, David G. Bear, Stephen C. Kowalczykowski

Research output: Contribution to journalArticlepeer-review

247 Scopus citations


A question remaining to be answered about RecA protein function concerns the role of ATP hydrolysis during the DNA-strand-exchange reaction. In this paper we describe the formation of joint molecules in the absence of ATP hydrolysis, using adenosine 5′-[γ-thio]triphosphate (ATP[γS]) as nucleotide cofactor. Upon the addition of double-stranded DNA, the ATP[γS]-RecA protein-single-stranded DNA presynaptic complexes can form homologously paired molecules that are stable after deproteinization. Formation of these joint molecules requires both homology and a free homologous end, suggesting that they are plectonemic in nature. This reaction is very sensitive to magnesium ion concentration, with a maximum rate and extent observed at 4-5 mM magnesium acetate. Under these conditions, the average length of heteroduplex DNA within the joint molecules is 2.4-3.4 kilobase pairs. Thus, RecA protein can form extensive regions of heteroduplex DNA in the presence of ATP[γS], suggesting that homologous pairing and the exchange of the DNA molecules can occur without ATP hydrolysis. A model for the RecA protein-catalyzed DNA-strand-exchange reaction that incorporates these results and its relevance to the mechanisms of eukaryotic recombinases are presented.

Original languageEnglish (US)
Pages (from-to)21-25
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - 1990
Externally publishedYes


  • DNA strand exchange
  • Genetic recombination
  • Homologous DNA pairing
  • Three-stranded DNA intermediate

ASJC Scopus subject areas

  • General


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