CATCHING THE RIGHT BREAK
How are ZFNs made? To start, zinc finger proteins (ZFP) are sequence-specific, DNA-binding proteins that activate gene expression. They are engineered to recognize unique sites within the genome. While ZFPs do not have the ability to cut DNA on their own, scientists can fuse a ZFP together with a DNA-cutting enzyme called nuclease—the “N” in ZFN. The marriage of ZFP to nuclease creates ZFN.
How do ZFNs work? Zinc finger proteins bring the zinc finger nuclease to the engineered location of the genome and the nuclease cuts the specific location. The double-stranded break (DSB) or cut activates the non-homologous end joining (NHEJ) repair pathway, this most often results in a disruption of a gene, useful for gene “knockouts”. If a repair template is delivered at the same time as the break, the homologous directed repair (HDR) pathway kicks in. This method is useful to “knockin” a gene. This video explains a potential application for zinc finger nucleases in HIV.