Patent ID: 7842489

Claim:
A single chain homing endonuclease, comprising a first variant of I-CreI having the amino acid sequence of SEQ ID NO:23 and a second variant of I-CreI having the amino acid sequence of SEQ ID NO:23 in a single polypeptide, wherein said first variant of I-CreI contains the following substitutions: one to six substitutions in the sequence of amino acid residues 26 to 40 and two to three substitutions in the sequence of amino acid residues 44 to 77, wherein in said first variant of I-CreI there is a substitution at positions 33, 68 and 77, and independently, said second variant of I-CreI contains the following substitutions: four to six substitutions in the sequence of amino acid residues 26 to 40 and two to three substitutions in the sequence of amino acid residues 44 to 77, wherein in said second variant of I-CreI there is a substitution at positions 26, 30, 32, 38, 44, and 68, wherein the endonuclease binds and cleaves DNA.