Site-specific recombination, also known as
conservative site-specific recombination, is a type of
genetic recombination in which
DNA strand exchange takes place between segments possessing at least a certain degree of
sequence homology. Site-specific
recombinases (SSRs) perform rearrangements of DNA segments by recognizing and binding to short DNA sequences (sites), at which they cleave the DNA backbone, exchange the two DNA helices involved and rejoin the DNA strands. While in some site-specific recombination systems just a
recombinase enzyme and the recombination sites is enough to perform all these reactions, in other systems a number of accessory proteins and/or accessory sites are also needed. Multiple
genome modification strategies, among these
recombinase-mediated cassette exchange (RMCE), an advanced approach for the targeted introduction of transcription units into predetermined genomic
loci, rely on the capacities of SSRs.