DNA recombinases are widely used in multicellular organisms to manipulate the structure of genomes, and to control gene expression.
These enzymes, derived from bacteria (bacteriophages) and fungi, catalyze directionally sensitive DNA exchange reactions between short (30–40 nucleotides) target site sequences that are specific to each recombinase.
These reactions enable four basic functional modules: excision/insertion, inversion, translocation and cassette exchange, which have been used individually or combined in a wide range of configurations to control gene expression.
The archaeon Sulfolobus solfataricus RadA recombinase catalyzes DNA pairing and strand exchange, central steps in recombinational repair.
RecA has a central role in the repair of replication forks stalled by DNA damage and in the bacterial sexual process of natural genetic transformation.