Zinc Finger Nucleases (ZFN)

What are ZFNs?

Zinc Finger Nucleases (ZFNs) are engineered DNA binding proteins that can be designed to bind to a wide variety of DNA sequences and function by introducing a double stranded break at a specified location in the genome.

ZFN gene editing

ZFNs are comprised of two component parts:

  • DNA-binding domain – made up of a chain of two-finger modules, each recognizing a unique hexamer (6 bp) sequence of DNA. Two-finger modules are stitched together to form a Zinc Finger Protein, with specificity of ≥ 24 bp
  • DNA-cleaving domain - nuclease domain of FokI

A high level of specificity is achieved with ZFNs because the FokI must dimerise for cleavage to occur. As such, a pair of ZFNs must be designed (one each side of the cut site on opposite strands) and only when dual binding occurs does dimerization and cleavage ensue.

ZFN gene editing

Once the cut has been achieved, the cell activates repair pathways to fix the damage. The non-homologous end joining (NHEJ) pathway is error-prone, and this can be particularly useful to introduce disruptions in the coding region of a gene. Small insertions and deletions are commonly introduced at the cut site, often resulting in disruption of the coding frame of an associated gene. ZFNs are therefore particularly effective at knocking out gene function.

Horizon has licensed this technology from Sigma-Aldrich for use in custom in vitro and exclusively for in vivo gene-editing projects.

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