Which system has single base-pair specificity through protein-DNA interaction?
Zinc finger nucleases link three to six fingers each contacting three base pairs, giving triplet recognition with context dependent cross-talk limiting true single base resolution. CRISPR relies on RNA-DNA pairing with mismatch tolerance. TALENs use central domain of 33-35 amino acid repeats where residues 12 and 13 called repeat variable di-residues dictate single nucleotide specificity: NI binds A, HD binds C, NG binds T, NN binds G. Each repeat recognizes exactly one base pair independently, providing genuine single base pair resolution through protein-DNA interaction ideal for precise targ
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
