title: A highly sensitive selection method for directed evolution of homing endonucleases.
abstract: Homing endonucleases are enzymes that catalyze DNA sequence specific double-strand breaks and can significantly stimulate homologous recombination at these breaks. These enzymes have great potential for applications such as gene correction in gene therapy or gene alteration in systems biology and metabolic engineering. However, homing endonucleases have a limited natural repertoire of target sequences, which severely hamper their applications. Here we report the development of a highly sensitive selection method for the directed evolution of homing endonucleases that couples enzymatic DNA cleavage with the survival of host cells. Using I-SceI as a model homing endonuclease, we have demonstrated that cells with wild-type I-SceI showed a high cell survival rate of 80-100% in the presence of the original I-SceI recognition site, whereas cells without I-SceI showed a survival rate <0.003%. This system should also be readily applicable for directed evolution of other DNA cleavage enzymes.
authors.affiliation: Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Zhilei
authors.initials: Z
authors.lastname: Chen
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
mesh_terms: D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000378:metabolism; D019020:Directed Molecular Evolution / Q000379:methods*; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D010957:Plasmids; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D014169:Transformation, Bacterial
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D004706:Endodeoxyribonucleases; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific