InterPro domain: IPR027434

Homing endonucleases are rare-cutting enzymes encoded by inteins and introns. They are found inserted within host genes in eukaryotes, bacteria, archaebacteria and viruses [ 1 ]. By making a site-specific double-strand break in the intronless or inteinless alleles, these nucleases create recombinogenic ends which engage in a gene conversion process that duplicates the intron or intein [ 2 , 3 ]. There are four families of homing endonucleases classified by the conserved sequence motifs LAGLIDADG, GIY-YIG, H-N-H and His-Cys box [ 4 , 4 ]. Endonucleases of the DOD family contain one or two copies of the 10-residue sequence known as a dodecapeptide or LAGLIDADG motif. LAGLIDADG endonucleases are either monomers, such as I-SceI, that are composed of two pseudosymmetric subdomains, or homodimers, such as I-CreI. In both cases, the LAGLIDADG endonuclease folds into a beta-saddle architecture, a common motif for nucleic acid binding proteins [ 5 ].

This superfamily represents the homing endonuclease domain.

1. Invasion of a multitude of genetic niches by mobile endonuclease genes. FEMS Microbiol. Lett. 185, 99-107
2. Homing endonucleases: keeping the house in order. Nucleic Acids Res. 25, 3379-88
3. Homing endonucleases: structure, function and evolution. Cell. Mol. Life Sci. 55, 1304-26
4. The conserved DNA-binding protein WhiA is involved in cell division in Bacillus subtilis. J. Bacteriol. 195, 5450-60
5. Crystal structures of I-SceI complexed to nicked DNA substrates: snapshots of intermediates along the DNA cleavage reaction pathway. Nucleic Acids Res. 36, 3287-96