Engineered transcription activator-like effector (TALE) domains and uses thereof
Engineered transcriptional activator-like effectors (TALEs) are versatile tools for genome manipulation with applications in research and clinical contexts. One current drawback of TALEs is their tendency to bind and cleave off-target sequence, which hampers their clinical application and renders applications requiring high-fidelity binding unfeasible. This disclosure provides engineered TALE domains and TALEs comprising such engineered domains, e.g., TALE nucleases (TALENs), TALE transcriptional activators, TALE transcriptional repressors, and TALE epigenetic modification enzymes, with improved specificity and methods for generating and using such TALEs.
1. A Transcription Activator-Like Effector Nuclease (TALEN), comprising
(a) a nuclease cleavage domain;
(b) a C-terminal domain conjugated to the nuclease cleavage domain;
(c) a TALE repeat array conjugated to the C-terminal domain; and
(d) an N-terminal domain conjugated to the TALE repeat array,
wherein
(i) the N-terminal domain comprises the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4, or a functional truncated version thereof; and/or
(ii) the C-terminal domain comprises an amino acid sequence that differs from the canonical C-terminal domain of SEQ ID NO: 22, in that it comprises one or more of the following amino acid replacements: K37Q, K38Q, K48Q, R49Q, R52Q, R53Q, R57Q, and R61Q, or a functional truncated version thereof.
2. The TALEN of claim 1 , wherein the C-terminal domain comprises a Q3 variant sequence of SEQ ID NO: 23.
3. The TALEN of claim 1 , wherein the C-terminal domain comprises a Q7 variant sequence of SEQ ID NO: 24.
4. The TALEN of claim 1 , wherein the nuclease cleavage domain is a FokI nuclease domain.
5. The TALEN of claim 1 , wherein the TALEN is a monomer.
6. The TALEN of claim 5 , wherein the TALEN monomer can dimerize with another TALEN monomer to form a TALEN dimer.
7. The TALEN of claim 6 , wherein the TALEN cleaves the target sequence upon dimerization.
8. The TALEN of claim 1 , wherein the TALEN binds a CCR5 target sequence, an ATM target sequence, or a VEGFA target sequence.
9. The TALEN of claim 1 , wherein the net charge of the C-terminal domain is between +5 and −5.
10. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1,in that at least 2 cationic amino acids of SEQ ID NO: 1 are replaced with an amino acid residue that exhibits no charge or a negative charge at physiological pH.
11. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1, in that at least 3 cationic amino acids of SEQ ID NO: 1 are replaced with an amino acid residue that exhibits no charge or a negative charge at physiological pH.
12. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1, in that at least 5 cationic amino acids of SEQ ID NO: 1 are replaced with an amino acid residue that exhibits no charge or a negative charge at physiological pH.
13. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1, in that at least 10 cationic amino acids of SEQ ID NO: 1 are replaced with an amino acid residue that exhibits no charge or a negative charge at physiological pH.
14. The TALEN of claim 1 , wherein the at least one cationic amino acid residue is arginine (R) or lysine (K).
15. The TALEN of claim 1 , wherein each amino acid residue that exhibits no charge or a negative charge at physiological pH is, independently, glutamine (Q) or glycine (G).
16. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1, in that at least one lysine or arginine residue is replaced with a glutamine residue.
17. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical N-terminal domain of SEQ ID NO: 1, in that at least one lysine or arginine residue is replaced with a glycine residue.
18. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical C-terminal domain of SEQ ID NO: 22, in that at least one lysine or arginine residue is replaced with a glutamine residue.
19. The TALEN of claim 1 , wherein the N-terminal domain comprises an amino acid sequence that differs from the canonical C-terminal domain of SEQ ID NO: 22, in that at least one lysine or arginine residue is replaced with a glycine residue.
20. The TALEN of claim 1 , wherein the C-terminal domain comprises an amino acid sequence that differs from the canonical C-terminal domain of SEQ ID NO: 22, in that it comprises one or more of the following amino acid replacements: K38Q, R52Q, and R61Q.
21. The TALEN of claim 1 , wherein the nuclease cleavage domain comprises a homodimeric FokI domain of SEQ ID NO: 26.
22. The TALEN of claim 1 , wherein the nuclease cleavage domain comprises a FokI-EL domain of SEQ ID NO: 27, a FokI-KK domain of SEQ ID NO: 28, a FokI-ELD domain of SEQ ID NO: 29, or a FokI-KKR domain of SEQ ID NO: 30.
23. A pharmaceutical composition comprising the TALEN of claim 1 and a pharmaceutically acceptable excipient.
24. A method of cleaving a target sequence in a nucleic acid molecule, comprising contacting a nucleic acid molecule comprising the target sequence with the TALEN of claim 1 , wherein the TALEN comprises a TALEN repeat array that binds the target sequence, and wherein the TALEN cleaves the target sequence.
25. The method of claim 24 , wherein the target sequence is comprised in a cell.
26. The method of claim 24 , wherein the target sequence is comprised in a subject.
27. The method of claim 24 , wherein the method comprises administering a pharmaceutical composition comprising the TALEN to the subject in an amount sufficient for the TALEN to bind and cleave the target site.
28. The method of claim 27 , wherein the TALEN binds a CCR5 target sequence, an ATM target sequence, or a VEGFA target sequence.