RecA is a 38 kilodalton protein essential for the repair and maintenance of DNA in bacteria. It functions as a recombinase and strand-exchange protein, catalyzing the central steps of homologous recombination by forming nucleoprotein filaments on single-stranded DNA. Structural and functional homologs to RecA have been found in all kingdoms of life. RecA serves as an archetype for this class of homologous DNA repair proteins. The homologous protein is called RAD51 in eukaryotes and RadA in archaea.
RecA has multiple activities, all related to DNA repair. As a recombinase, it mediates ATP-dependent strand exchange between homologous DNA molecules, driving the key pairing and heteroduplex formation steps of recombinational repair. In the bacterial SOS response, it functions as a co-protease in the autocatalytic cleavage of the LexA repressor and the λ repressor.
