Classification and evolutionary history of the single-strand annealing proteins, RecT, Redβ, ERF and RAD52

There are three evolutionarily distinct superfamilies of SSAPs, namely the RecT/Redbeta, ERF, and RAD52, that have different sequence conservation patterns and predicted folds. All these SSAPs appear to be primarily of bacteriophage origin and have been acquired by numerous phylogenetically distant cellular genomes. They generally occur in predicted operons encoding one or more of a set of conserved DNA recombination proteins that appear to be the principal functional partners of the SSAPs.