Base triplet stepping by the Rad51/RecA family of recombinases

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 p...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2015-08, Vol.349 (6251), p.977-981
Main Authors: Lee, Ja Yil, Terakawa, Tsuyoshi, Qi, Zhi, Steinfeld, Justin B., Redding, Sy, Kwon, YoungHo, Gaines, William A., Zhao, Weixing, Sung, Patrick, Greene, Eric C.
Format: Article
Language:English
Subjects:
Bacteria
Cell division
Deoxyribonucleic acid
DNA
Enzymes
Exchange
Genetic recombination
Genetics
Matching
Recognition
Strands
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Summary: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.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aab2666