What are TALENs?

Transcription Activator-Like Effector Nucleases (TALENs) are a class of engineered nucleases (or enzymes) that can be used for gene editing. These proteins are derived from Xanthomonas bacteria in which they bind to and activate host promoters. TALENs are a two-component system comprising of a DNA binding domain and the FokI DNA-cleaving domain. TALENs enable editing of the genome in specific locations. In 2009, it was shown that the binding specificity of the DNA binding domain of TAL effectors could be altered by modifiying two amino acids (referred to as a repeat variable diresidue or RVD) within the highly conserved 33-34 amino acid repeats that made up the domain. Consequently, DNA recognition sequences could be constructed by assembling the right combination of repeat sequences. TALENs, ZFNs, and CRISPR are common tools for gene editing.