Engineered TAL Effector Technology

Welcome to, a comprehensive resource of information and resources for practicing engineered TAL (Transcription Activator-Like) effector technology. This website, created and maintained by the Joung Lab at the Massachusetts General Hospital, will strive to provide a “one-stop” location for those interested in constructing TAL effector proteins with customized DNA-binding specificities.

Naturally occurring TAL effectors harbor highly conserved repeat domains that each bind to a single base pair of DNA. The identities of two residues (referred to as repeat variable di-residues or RVDs) in these 33 to 35 amino acid repeats are associated with the binding specificity of these domains. Recent work from multiple labs has shown that these repeats can be joined together to create extended arrays capable of binding to target DNA sequences of interest. Efficient DNA-binding by TAL effector repeat arrays also requires the presence of additional N-terminal and C-terminal amino acid sequences derived from naturally occurring TAL effectors. Over the past several years, a variety of different assembly platforms have been developed that enable interested researchers to assemble DNA encoding customized TAL effector repeat arrays.

Engineered TAL repeat arrays can be fused to functional domains to create artificial proteins with novel functions. Fusion of TAL effector repeat arrays to the non-specific FokI nuclease domain has resulted in the production of customizable endonucleases known as TAL effector nucleases (TALENs). Repair of double-strand DNA breaks induced by TALENs can be exploited to induce targeted insertion/deletion mutations (by non-homologous end-joining-mediated repair) or specific substitutions or insertions (by homology-directed repair). TAL effector repeat arrays have also been fused to transcriptional regulatory domains to create artificial transcription factors.

We hope that the information provided on this webpage will be helpful to those interested in making their own customized TAL repeat arrays. We also welcome suggestions for additional materials about TAL effector technology not yet listed on these pages.


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