Definition |
The recognition site for a particular site-specific recombinase, an enzyme that mediates a recombination exchange reaction between two DNA templates, each containing a copy of the recognition site. The recognition site contains perfect inverted repeats flanking an asymmetric spacer. Under normal conditions, the two recognition sites are identical and are reformed during the recombination event, and thus the reaction is bidirectional: recombination can occur in both 'forward' and 'reverse' directions. However, recognition sites can be mutated to drive the directionality of the reaction: different classes of site may be combined so that recombination can occur in one direction, but produces reformed sites that are no longer compatible. In addition, mutually exclusive sites have been engineered for some recombinases. Recombinases can be used to generate many different types of genetic modification, with the outcome being influenced by the relative orientation (direct or inverted), relative location and composition of the two recognition sites. The types of possible modification include deletion of DNA, generation of chromosomal rearrangements, integration of DNA into the genome, and replacement of genetic material with that from a donor plasmid using recombination-mediated cassette exchange (RMCE).[ FlyBase:FBrf0231034 ] |