Alteration of restriction endonuclease specificity by genetic selection

摘要

Methods and compositions are provided for altering the DNA recognition and cleavage characteristics of an endonuclease without prior knowledge of the endonuclease's three-dimensional structure and/or amino acid residues responsible for activity and/or specificity. Methods include subjecting a mutagenized endonuclease gene library to a genetic selection in prokaryotic cells which tolerate the expression of mutated endonuclease and where the endonuclease is active and determining the altered recognition-site specificity for the endonuclease.