Engineered CRISPR-CAS9 nucleases with altered PAM specificity
Engineered CRISPR-Cas9 nucleases with altered and improved PAM specificities and their use in genomic engineering, epigenomic engineering, and genome targeting.
1. An isolated variant Staphylococcus aureus Cas9 (SaCas9) protein comprising an amino sequence that has at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 2, wherein the amino acid corresponding to E782 of SEQ ID NO: 2, the amino acid corresponding to N968 of SEQ ID NO: 2, and/or the amino acid corresponding to R1015 of SEQ ID NO: 2 is mutated in the variant SaCas9 protein, and wherein the variant SaCas9 protein binds to a guide RNA and a target DNA.
2. The variant SaCas9 protein of claim 1 , wherein the amino acid corresponding to E782 is mutated to K, the amino acid corresponding to N968 is mutated to K, and/or the amino acid corresponding to R1015 is mutated to Q or H in the variant SaCas9 protein.
3. The variant SaCas9 protein of claim 1 , wherein the amino acid corresponding to E782 is mutated to K, the amino acid corresponding to N968 is mutated to K, and the amino acid corresponding to R1015 is mutated to H in the variant SaCas9, and optionally wherein the amino acid corresponding to E735 of SEQ ID NO: 2 is mutated to K, the amino acid corresponding to K929 of SEQ ID NO: 2 is mutated to R, the amino acid corresponding to A1021 of SEQ ID NO: 2 is mutated to T, or the amino acid corresponding to K1044 of SEQ ID NO: 2 is mutated to N in the variant SaCas9 protein.
4. The variant SaCas9 protein of claim 1 , wherein the amino acid corresponding to D10 of SEQ ID NO: 2, the amino acid corresponding to D556 of SEQ ID NO: 2, the amino acid corresponding to H557 of SEQ ID NO: 2, and/or the amino acid corresponding to N580 of SEQ ID NO: 2 is mutated in the variant SaCas9 protein.
5. The variant SaCas9 protein of claim 4 , wherein the amino acid corresponding to D10 is mutated to A, the amino acid corresponding to D556 is mutated to A, the amino acid corresponding to H557 is mutated to A, and/or the amino acid corresponding to N580 is mutated to A in the variant SaCas9 protein.
6. The variant SaCas9 protein of claim 4 , wherein:
(i) the amino acid corresponding to D10 is mutated to A and the amino acid corresponding to H557 is mutated to A in the variant SaCas9 protein, or
(ii) the amino acid corresponding to D10 is mutated to A, the amino acid corresponding to D556 is mutated to A, the amino acid corresponding to H557 is mutated to A, and the amino acid corresponding to N580 is mutated to A in the variant SaCas9 protein.
7. A fusion protein comprising the variant SaCas9 protein of claim 1 , fused to a heterologous functional domain, with an optional intervening linker, wherein the linker does not interfere with activity of the fusion protein.
8. The fusion protein of claim 7 , wherein the heterologous functional domain is a transcriptional activation domain.
9. The fusion protein of claim 8 , wherein the transcriptional activation domain is from VP64 or NF-kB p65.
10. The fusion protein of claim 7 , wherein the heterologous functional domain is a transcriptional silencer or transcriptional repression domain.
11. The fusion protein of claim 10 , wherein the transcriptional repression domain is a Krueppel-associated box (KRAB) domain, ERF repressor domain (ERD), or mSin3A interaction domain (SID).
12. The fusion protein of claim 10 , wherein the transcriptional silencer is Heterochromatin Protein 1 (HP1).
13. The fusion protein of claim 7 , wherein the heterologous functional domain is an enzyme that modifies the methylation state of DNA.
14. The fusion protein of claim 13 , wherein the enzyme that modifies the methylation state of DNA is a DNA methyltransferase (DNMT) or a Ten-Eleven-Translocation (TET) protein.
15. The fusion protein of claim 14 , wherein the TET protein is TET1.
16. The fusion protein of claim 7 , wherein the heterologous functional domain is an enzyme that modifies a histone subunit.
17. The fusion protein of claim 16 , wherein the enzyme that modifies a histone subunit is a histone acetyltransferase (HAT), histone deacetylase (HDAC), histone methyltransferase (HMT), or histone demethylase.
18. The fusion protein of claim 7 , wherein the heterologous functional domain is a biological tether.
19. The fusion protein of claim 18 , wherein the biological tether is MS2, Csy4 or lambda N protein.
20. The fusion protein of claim 7 , wherein the heterologous functional domain is FokI.
21. A method of altering the genome of an isolated cell, the method comprising contacting the cell with the variant SaCas9 protein of claim 1 , and a guide RNA having a region complementary to a selected portion of the genome of the cell, whereby the genome of the cell is altered.
22. The method of claim 21 , wherein the variant SaCas9 protein comprises one or more of a nuclear localization sequence, cell penetrating peptide sequence, and/or affinity tag.
23. A method of altering an isolated double stranded DNA (dsDNA) molecule, the method comprising contacting the dsDNA molecule with the variant SaCas9 protein of claim 1 , and a guide RNA having a region complementary to a selected portion of the dsDNA molecule, whereby the dsDNA molecule is altered.
24. The variant SaCas9 protein of claim 1 , wherein the variant SaCas9 comprises the amino acid sequence of SEQ ID NO: 2, except the amino acid corresponding to E782 of SEQ ID NO: 2, the amino acid corresponding to N968 of SEQ ID NO: 2, and/or the amino acid corresponding to R1015 of SEQ ID NO: 2 is mutated in the variant SaCas9 protein.