Definition: Transcription Activator-Like Effector Nucleases (TALENs) are a class of engineered nuclease (or enzyme) that can be used for gene editing.
These proteins are derived from Xanthomonas bacteria in which they are used to bind and activate host promoters, TALEN are a two component system comprising a DNA binding domain and the FokI DNA-cleaving domain. TALEN enables 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 (refered 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 the most common forms of engineered gene editing.
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