- Site-specific genome editing at will
Transcription activator-like (TAL) effectors can recognize and bind DNA sequences through a central repeat domain consisting of a variable number of ~34 amino acid repeats. The residues at the 12th and 13th positions of each repeat are hyper-variable. There appears to be a simple one-to-one code between these two critical amino acids in each repeat and each DNA base in the target sequence, e.g. NI = A, HD = C, NG = T, and NN = G or A.
TAL effectors have been utilized to create site-specific gene-editing tools by fusing target sequence-specific TAL effectors to nucleases(TALENs), transcription factors (TALE-TFs) and other functional domains. These fusion proteins can recognize and bind chromosome target sequences specifically and execute their gene-editing functions, such as gene knockout, knockin (with donor plasmid), modification, activation, repression and more.
Unlike zinc fingers’ nucleotide triplet recognition, TAL effector domains recognize single nucleotides, which allows researchers to be able to specifically target whatever sequence they want with lower cost and greater flexibility in design.
Take advantage of the benefits of Genome-TALER™ for your genome editing.
- Targeting any gene in any cell
- Highly sequence-specific genome editing
- For gene knockout, knockin, mutagenesis, activation, repression and more
- Flexible TAL effector design of binding and functional domains, such as TALEN and TALE-TF
-For gene modification, gene knockout & gene knockin
A TAL effector nuclease (TALEN) contains a TALE DNA binding domain fused to the FokI nuclease. Two TALENs must bind on each side of the targeted site for FokI to dimerize and cut.
TALENs induce a site-specific double-strand break (DSB), which the cellular repair mechanism of non-homologous end joining (NHEJ) can then reconnect the DNA and induce insertion or deletion errors at the site of the break. Alternatively, an exogenous double-stranded donor DNA fragment can be introduced into the genome at the DSB by homologous recombination (HR).
TALENs have been used to generate stably modified human embryonic stem cell and induced pluripotent stem cell (IPSCs) clones, and to generate knockout organisms such as rats, C. elegans, and zebrafish. TALENs can also be used in site-specific gene knockin when co-transfected with a donor plasmid.
Figure 1. Illustration of TALEN design
|Figure 2. TALEN-mediated gene knockout. (left) TALEN-created DSBs are repaired by NHEJ. (right) TALEN-created DSBs are repaired by the insertion of selection markers (or other genetic element) from a donor plasmid through HR.|
-For gene activation (and more)
The TALE-TF contains a TALE DNA binding domain fused to the VP64 transcription activator. It is a powerful tool to selectively modulate gene expression in eukaryotic cells with exquisite specificity.
Figure 3. Illustration of TALE-TF design
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Genome-TALER™ human AAVS1 safe harbor gene knock-in kit is designed to specifically transfer your gene of interest, selection marker or other genetic element from a donor plasmid into the AAVS1 safe harbor site in human chromosome 19 via TALEN-mediated homologous recombination (HR). HR is a natural DNA repair mechanism that occurs in response to DNA double-strand breaks (DSBs). The DSBs here are created by AAVS1-specific TALENs.
Genome-TALER™ human AAVS1 safe harbor gene knock-in clones are a collection of more than 18,000 ORF knock-in donor clones that are constructed for specially transferring the ORFs of customers' genes of interest from a AAVS1 donor plasmid to the AAVS1 site for safe integration and single copy gene expression. These clones are compatible with the Genome-TALER™ human AAVS1 safe harbor gene knock-in kit.