High efficiency base editors comprising Gam
Some aspects of this disclosure provide strategies, systems, reagents, methods, and kits that are useful for the targeted editing of nucleic acids, including editing a single site within the genome of a cell or subject, e.g., within the human genome. In some embodiments, fusion proteins comprise a Gam protein, a napDNAbp, and a cytidine deaminase. In some embodiments, the fusion proteins further comprise a UGI domain. In some embodiments, methods for targeted nucleic acid editing are provided. In some embodiments, reagents and kits for the generation of targeted nucleic acid editing proteins, e.g., fusion proteins of a Gam protein, a cytidine deaminase and nucleic acid editing proteins or domains, are provided.
1. A fusion protein comprising: (i) a nucleic acid programmable DNA binding protein (napDNAbp) domain; (ii) a cytidine deaminase domain; and (iii) a Gam protein domain.
2. The fusion protein of claim 1 further comprising (iv) a first uracil glycosylase inhibitor (UGI) domain.
3. The fusion protein of claim 1 , wherein the nucleic acid programmable DNA binding protein (napDNAbp) domain is a Cas9 domain.
4. The fusion protein of claim 3 , wherein the Cas9 domain is a nuclease active Cas9 domain, a Cas9 nickase (nCas9) domain, or a nuclease inactive Cas9 (dCas9) domain.
5. The fusion protein of claim 3 , wherein the Cas9 domain is an nCas9 domain that comprises a D10A mutation in the amino acid sequence provided in SEQ ID NO: 6.
6. The fusion protein of claim 2 further comprising a second UGI domain.
7. The fusion protein of claim 6 , wherein at least one of the first UGI domain and the second UGI domain comprises an amino acid sequence that is at least 90% identical to SEQ ID NO: 362.
8. The fusion protein of claim 1 , wherein the cytidine deaminase domain is a deaminase from the apolipoprotein B mRNA-editing complex (APOBEC) family of deaminases.
9. The fusion protein of claim 1 , wherein the cytidine deaminase domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of any one of SEQ ID NOs: 323-361.
10. The fusion protein of claim 2 , wherein the fusion protein comprises the structure: NH 2 -[Gam protein domain]-[cytidine deaminase domain]-[napDNAbp domain]-[first UGI domain]-COOH, and wherein each instance of “]-[” comprises an optional linker.
11. The fusion protein of claim 6 , wherein the fusion protein comprises the structure: NH 2 -[Gam protein domain]-[cytidine deaminase domain]-[napDNAbp domain]-[first UGI domain]-[second UGI domain]-COOH, and wherein each instance of “]-[” comprises an optional linker.
12. The fusion protein of claim 1 , wherein the Gam protein domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 9.
13. The fusion protein of claim 1 , wherein the Gam protein domain comprises the amino acid sequence of SEQ ID NO: 9.
14. The fusion protein of claim 1 , wherein the fusion protein comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 394 or 396.
15. The fusion protein of claim 1 , wherein the fusion protein comprises the amino acid sequence of SEQ ID NO: 394 or 396.
16. A complex comprising the fusion protein of claim 1 and a guide RNA bound to the napDNAbp domain of the fusion protein.
17. A method comprising contacting a nucleic acid molecule with the fusion protein of claim 1 and a guide RNA, wherein the guide RNA comprises a sequence of at least 10 contiguous nucleotides that is complementary to a target sequence in the genome of an organism, wherein the target sequence comprises a target base pair.
18. The method of claim 17 , wherein the contacting results in less than 1% indel formation upon base editing.
19. A pharmaceutical composition comprising the complex of claim 16 .
20. The fusion protein of claim 3 , wherein the Cas9 domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 317 or NO: 311.
21. The fusion protein of claim 1 , wherein the cytidine deaminase domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 349.