Transcription activator like effectors (TALEs) are natural typeIII effector proteins secreted by numerous species of Xanthomonas to modulate gene expression in host plants and to facilitate bacterial colonization and survival. Recent studies of TALEs have revealed an elegant code linking the repetitive region of TALEs with their target DNA-binding site (Boch et al., Science 2009; Moscou et al., Science 2009). Common among the entire family of TALEs is a highly conserved and repetitive region within the middle of the protein, consisting of tandem repeats of mostly 33 or 34 amino acid segments. Repeat monomers differ from each other mainly in amino acid positions 12 and 13 (repeat variable di-residues), and recent computational and functional analyses have revealed a strong correlation between unique pairs of amino acids at positions 12 and 13 and the corresponding nucleotide in the TALE-binding site: NI to A, HD to C, NG to T, NK for G, NN for G or A, NS for all bases (Boch et al., Science 2009; Moscou et al., Science 2009; Morbitzer et al., PNAS 2010; Miller et al., Nat. Biotech 2010).
Recent studies have tested the modularity of the TALE DNA binding code and have demonstrated that custom TALEs can be designed to recognize specific DNA sequences in a number of different cell types including plant and mammalian cells. Custom TALEs can be tethered to a variety of effector domains to modulate transcription of endogenous genes in the genome as well as generate site-specific double strand break to catalyze homologous recombination for genome engineering applications.
These pages include protocols as well as reagents for constructing designer TALEs as well as deploying TALEs in experimental applications (Zhang, Cong et al., Nature Biotechnology 2011)."