Homologous recombination plays key roles in double-strand break repair, rescue, and repair of stalled replication forks and meiosis. The broadly conserved Rad51/RecA family of recombinases catalyzes the DNA strand invasion reaction that takes place during homologous recombination. We have established single-stranded (ss)DNA curtain assays for measuring individual base triplet steps during the early stages of strand invasion. Here, we examined how base triplet stepping by RecA, Rad51, and Dmc1 is affected by DNA sequence imperfections, such as single and multiple mismatches, abasic sites, and single nucleotide insertions.
