Compositions and methods directed to CRISPR/Cas genomic engineering systems
The invention relates to engineered CRISPR/Cas9 systems for genomic modification in mammalian cells. The present specification describes the design and testing of a polynucleotide encoding the Streptococcus pyogenes ( S. pyogenes ) Cas9 protein, where the nucleotide sequence has been optimized for expression in mammalian cells. The specification also describes all-in-one systems for RNA-guided genome engineering in mammalian cells, including human cells.
1. An expression construct comprising:
(a) a first polynucleotide encoding a Cas9 protein, wherein the first polynucleotide comprises the nucleotide sequence of positions 91 through 4191 of SEQ ID NO: 1, and
(b) a second polynucleotide encoding a guide RNA, said guide RNA comprising
(i) a crRNA-tracrRNA chimeric transcript comprising the nucleotide sequence of positions 49 through 131 of SEQ ID NO: 6, and
(ii) a targeting sequence complementary to a target nucleic acid, where the targeting sequence is operably linked to the crRNA-tracrRNA chimeric transcript.
2. The expression construct of claim 1 , wherein the expression construct is a mammalian expression construct.
3. The expression construct of claim 1 , wherein the Cas9 protein is a Streptococcus pyogenes Cas9 protein.
4. The expression construct of claim 1 , wherein the first polynucleotide further encodes at least one nuclear localization signal.
5. The expression construct of claim 1 , wherein the first polynucleotide comprises the nucleotide sequence of positions 40 through 4242 of SEQ ID NO: 1.
6. A system for cleavage of a target nucleic acid in a mammalian cell, the system comprising:
(a) a mammalian expression construct comprising:
i) a first polynucleotide encoding a Cas9 protein, wherein the first polynucleotide comprises the nucleotide sequence of positions 91 through 4191 of SEQ ID NO: 1, and
ii) a second polynucleotide encoding a guide RNA, said guide RNA comprising:
(A) a crRNA-tracrRNA chimeric transcript comprising the nucleotide sequence of positions 49 through 131 of SEQ ID NO: 6, and
(B) a targeting sequence complementary to the target nucleic acid, where the targeting sequence is operably linked to the crRNA-tracrRNA chimeric transcript; and,
(b) a mammalian cell comprising the target nucleic acid, wherein the first polynucleotide and second polynucleotide are capable of expression from the mammalian expression construct when that construct is within the mammalian cell.
7. The system of claim 6 , wherein the cleavage is a double stranded break.
8. The system of claim 6 , wherein the target nucleic acid is a genomic nucleic acid.
9. The system of claim 6 , wherein the target nucleic acid is complementary to an endogenous mammalian nucleotide sequence.
10. The system of claim 6 , wherein the system is a multiplex system, further comprising at least a second guide RNA for cleavage of a second target nucleic acid in the mammalian cell, the second guide RNA comprising:
(A) a second crRNA-tracrRNA chimeric transcript, and
(B) a second targeting sequence complementary to the second target nucleic acid, where the second targeting sequence is operably linked to the crRNA-tracrRNA chimeric transcript.
11. A system for modification of a genomic target nucleic acid in a mammalian cell, the system comprising:
(a) a mammalian expression construct comprising:
i) a first polynucleotide encoding a Cas9 protein, wherein the first polynucleotide comprises the nucleotide sequence of positions 91 through 4191 of SEQ ID NO: 1, and
ii) a second polynucleotide encoding a guide RNA, said guide RNA comprising:
(A) a crRNA-tracrRNA chimeric transcript comprising the nucleotide sequence of positions 49 through 131 of SEQ ID NO: 6, and
(B) a targeting sequence complementary to the genomic target nucleic acid, where the targeting sequence is operably linked to the crRNA-tracrRNA chimeric transcript;
(b) a donor polynucleotide comprising nucleotide sequence having homology to the genomic target nucleic acid or homology to nucleotide sequence flanking the genomic target nucleic acid; and
(c) a mammalian cell comprising the genomic target nucleic acid, wherein the first polynucleotide and second polynucleotide are capable of expression from the mammalian expression construct when that construct is within the mammalian cell.
12. The system of claim 11 , wherein the genomic target nucleic acid is an endogenous mammalian nucleotide sequence.
13. The system of claim 11 , wherein the system is a multiplex system, further comprising at least a second guide RNA comprising a crRNA-tracrRNA chimeric transcript operably linked to a second targeting sequence complementary to a second genomic target nucleic acid.
14. The system of claim 11 , wherein the mammalian expression construct further comprises at least one nucleotide sequence that permits the identification or selection of mammalian cells that contain a modification of the genomic target nucleic acid.
15. The system of claim 11 , wherein the modification of the genomic target nucleic acid is a replacement of nucleotides from the genomic target with nucleotides encoded by the donor polynucleotide.