A mutational analysis of DNA binding and cleavage by the homing endonuclease PI-SceI

We have carried out an extensive mutational analysis of PI-SceI, the best s tudied intein-like homing endonuclease of the LAGLIDADG family, to find out which amino acid residues are involved in substrate binding and processing . Our analysis was focused on domain I, in which two regions were shown to be in contact with DNA, and on domain II, in which the amino acid residues making up catalytic centers I and II were identified and their role in cata lysis investigated. As a result of our comprehensive mutational analysis a model is presented for DNA binding and cleavage by PI-SceI.