Dna Binding : A Rna Binding Motif Essay

Alongside CRISPR-Cas9 in site specific genome editing are ZFNs and TALENs. ZFNs are a DNA-binding motif assembled as ββα that utilizes a roughly thirty amino acid protein with DNA recognizing amino acids at the alpha helix (Gaj, Gersbach, & Barbas, 2013). These groups of amino acids usually recognize DNA in segments of three. This does not present much specificity in a genome. Therefore multiple DNA-binding motifs need to be combined to create specificity and result in highly specific polypeptides of repeating zinc finger complexes that recognize nearly eighteen base pair lengths. This structure results in relatively large molecules and the size increases due to ZFNs main nucleases only functioning as dimers. A dsDNA break requires two ZFNs designed specifically for the target DNA site and attached to a large nuclease. ZFNs can have complicated interactions with itself and the target sequence, which makes them particularly more difficult to produce effectively. TALEN also works with DNA-binding motifs; however, each thirty amino acid motif recognizes a single nucleotide. While this does simplify the complex nature of designing ZFNs, TALENs can get increasingly large and limit their applications within the cell or even limit their ability to be virally inserted into an organism. Both DNA-binding motif techniques are more complex and expensive to design than the CRISPR-Cas9 that can be broken down all the way to a complimentary RNA strand and a single nuclease (Gaj,…