Figure 2.

Protein-guided gene-editing tools. (A) A pair of zinc-finger nucleases comprised of an array of zinc-finger protein domains that bind to 3 nucleotides each, fused to a FokI endonuclease domain. The dimerization of two of these complexes on adjacent DNA strands in an inverted orientation generates a DSB at a site determined by the protein DNA binding domains. (B) A pair of transcriptional activator-like effector nucleases (TALEN) comprised of repeating TALE domains that each bind to a single nucleotide. These complexes are fused to a FokI endonuclease domain that binds to opposing DNA strands and arranged in an inverted tail-to-tail orientation, with optimized spacing determined by the TALE binding domains. Dimerization of these complexes enables the FokI domains to activate a DSB at the target site. This figure has been adapted from [6].