Site-specific recombination plays an important role in DNA rearrangement in prokaryotic organisms. Two types of site-specific recombination are known to occur:

1. Recombination between inverted repeats resulting in the reversal of a DNA segment.
2. Recombination between repeat sequences on two DNA molecules resulting in their cointegration, or between repeats on one DNA molecule … expand

Site-specific recombination plays an important role in DNA rearrangement in prokaryotic organisms. Two types of site-specific recombination are known to occur:

1. Recombination between inverted repeats resulting in the reversal of a DNA segment.
2. Recombination between repeat sequences on two DNA molecules resulting in their cointegration, or between repeats on one DNA molecule resulting in the excision of a DNA fragment.

Site-specific recombination is characterised by a strand exchange mechanism that requires no DNA synthesis or high energy cofactor; the phosphodiester bond energy is conserved in a phospho-protein linkage during strand cleavage and re-ligation.

Two unrelated families of recombinases are currently known [ PUBMED:3011407 ]. The first, called the 'phage integrase' family, groups a number of bacterial phage and yeast plasmid enzymes. The second [ PUBMED:2896291 ], called the 'resolvase' family, groups enzymes which share the following structural characteristics: an N-terminal catalytic and dimerization domain that contains a conserved serine residue involved in the transient covalent attachment to DNA, and a C-terminal helix-turn-helix DNA-binding domain ( IPR006120 ).