page_title: Transcription activator-like effector nuclease
section_title: Engineering TALEN constructs
hierarchical_section_title: Transcription activator-like effector nuclease / Engineering TALEN constructs
context_page_description: Transcription activator-like effector nucleases are restriction enzymes that can be engineered to cut specific sequences of DNA. They are made by fusing a TAL effector DNA-binding domain to a DNA cleavage domain. Transcription activator-like effectors can be engineered to bind to practically any desired DNA sequence, so when combined with a nuclease, DNA can be cut at specific locations. The restriction enzymes can be introduced into cells, for use in gene editing or for genome editing in situ, a technique known as genome editing with engineered nucleases. Alongside zinc finger nucleases and CRISPR/Cas9, TALEN is a prominent tool in the field of genome editing.
context_section_description: The simple relationship between amino acid sequence and DNA recognition of the TALE binding domain allows for the efficient engineering of proteins. In this case, artificial gene synthesis is problematic because of improper annealing of the repetitive sequence found in the TALE binding domain. One solution to this is to use a publicly available software program (DNAWorks) to calculate oligonucleotides suitable for assembly in a two step PCR oligonucleotide assembly followed by whole gene amplification. A number of modular assembly schemes for generating engineered TALE constructs have also been reported. Both methods offer a systematic approach to engineering DNA binding domains that is conceptually similar to the modular assembly method for generating zinc finger DNA recognition domains.
caption: Workflow of genome editing of Your Favorite Gene (YFG) using TALEN. The target sequence is identified, a corresponding TALEN sequence is engineered and inserted into a plasmid. The plasmid is inserted into the target cell where it is translated to produce the functional TALEN, which enters the nucleus and binds and cleaves the target sequence. Depending on the application, this can be used to introduce an error (to knock out a target gene) or to introduce a new DNA sequence into the target gene.