biostudies-literatureRistic DNCI NIH HHS155-67https://www.ebi.ac.uk/biostudies/studies/S-EPMC3017611biostudies-literatureUnknown39(1)The defining event in homologous recombination is the exchange of base-paired partners between a single-stranded (ss) DNA and a homologous duplex driven by recombinase proteins, such as human RAD51. To understand the mechanism of this essential genome maintenance event, we analyzed the structure of RAD51-DNA complexes representing strand exchange intermediates at nanometer resolution by scanning force microscopy. Joint molecules were formed between substrates with a defined ssDNA segment and homologous region on a double-stranded (ds) partner. We discovered and quantified several notable architectural features of RAD51 joint molecules. Each end of the RAD51-bound joints had a distinct structure. Using linear substrates, a 10-nt region of mispaired bases blocked extension of joint moleculesNucleic acids researchVisualizing RAD51-mediated joint molecules: implications for recombination mechanism and the effect of sequence heterology.PMC30176115P01CA092584P01 CA092584Kanaar RRistic DWyman CfalseVisualizing RAD51-mediated joint molecules: implications for recombination mechanism and the effect of sequence heterology.The defining event in homologous recombination is the exchange of base-paired partners between a single-stranded (ss) DNA and a homologous duplex driven by recombinase proteins, such as human RAD51. To understand the mechanism of this essential genome maintenance event, we analyzed the structure of RAD51-DNA complexes representing strand exchange intermediates at nanometer resolution by scanning force microscopy. Joint molecules were formed between substrates with a defined ssDNA segment and homologous region on a double-stranded (ds) partner. We discovered and quantified several notable architectural features of RAD51 joint molecules. Each end of the RAD51-bound joints had a distinct structure. Using linear substrates, a 10-nt region of mispaired bases blocked extension of joint molecules2011-01-01T00:00:00Z2011 Jan2025-04-04T19:18:16.357Z2019-03-27T00:37:57ZS-EPMC30176112081792810.1093/nar/gkq766