Base triplet stepping by the Rad51/RecA family of recombinases

Ja Yil Lee, Tsuyoshi Terakawa, Zhi Qi, Justin B. Steinfeld, Sy Redding, Young Ho Kwon, William A. Gaines, Weixing Zhao, Patrick Sung, Eric C. Greene

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


DNA strand exchange plays a central role in genetic recombination across all kingdoms of life, but the physical basis for these reactions remains poorly defined. Using single-molecule imaging, we found that bacterial RecA and eukaryotic Rad51 and Dmc1 all stabilize strand exchange intermediates in precise three-nucleotide steps. Each step coincides with an energetic signature (0.3 kBT) that is conserved from bacteria to humans. Triplet recognition is strictly dependent on correct Watson-Crick pairing. Rad51, RecA, and Dmc1 can all step over mismatches, but only Dmc1 can stabilize mismatched triplets. This finding provides insight into why eukaryotes have evolved a meiosis-specific recombinase. We propose that canonical Watson-Crick base triplets serve as the fundamental unit of pairing interactions during DNA recombination.

Original languageEnglish (US)
Pages (from-to)977-981
Number of pages5
Issue number6251
StatePublished - Aug 28 2015
Externally publishedYes

ASJC Scopus subject areas

  • General


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