RECOMBINANT TYPE II RESTRICTION ENDONUCLEASES, MmeI AND RELATED ENDONUCLEASES AND METHODS FOR PRODUCTING THE SAME

摘要

In accordance with the present invention, there is provided a DNA (deoxyribonucleic acid) fragment which encodes the MmeI type II restriction endonuclease enzyme. This one polypeptide possesses two related enzymatic functions; namely an endonuclease activity which recognizes the DNA sequence 5'-TCC(Pu)AC-3' and cleaves as indicated by the arrows: 5 ' -TCCRAC (N20) †“-3 ' 3'-AGGYTG(N18)†‘-5' and a second enzymatic activity that recognizes the same DNA sequence, 5'-TCC(Pu)AC-3', but modifies this sequence by the addition of a methyl group to prevent cleavage by the MmeI endonuclease activity.