GIYX(10-11)YIG family of class I homing endonucleases C-terminus (GIY-YIG_Cterm). Homing endonucleases promote the mobility of intron or intein by recognizing and cleaving a homologous allele that lacks the sequence. They catalyze a double-strand break in the DNA near the insertion site of that element to facilitate homing at that site. Class I homing endonucleases are sorted into four families based on the presence of these motifs in their respective N-termini: LAGLIDADG, His-Cys box, HNH, and GIY-YIG. This CD contains several but not all members of the GIY-YIG family. The C-terminus of GIY-YIG is a DNA-binding domain which is separated from the N-terminus by a long, flexible linker. The DNA-binding domain consists of a minor-groove binding alpha-helix, and a helix-turn-helix. Some also contain a zinc finger (i.e. I-TevI) which is not required for DNA binding or catalysis, but is a component of the linker and directs the catalytic domain to cleave the homing site at a fixed distance from the intron insertion site.
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