Methods and compositions for RNA-directed target DNA modification and for RNA-directed modulation of transcription
The present disclosure provides a DNA-targeting RNA that comprises a targeting sequence and, together with a modifying polypeptide, provides for site-specific modification of a target DNA and/or a polypeptide associated with the target DNA. The present disclosure further provides site-specific modifying polypeptides. The present disclosure further provides methods of site-specific modification of a target DNA and/or a polypeptide associated with the target DNA The present disclosure provides methods of modulating transcription of a target nucleic acid in a target cell, generally involving contacting the target nucleic acid with an enzymatically inactive Cas9 polypeptide and a DNA-targeting RNA. Kits and compositions for carrying out the methods are also provided. The present disclosure provides genetically modified cells that produce Cas9; and Cas9 transgenic non-human multicellular organisms.
1. A method of modifying a target DNA molecule in a cell, the method comprising contacting a target DNA molecule inside of a cell with:
(a) a Cas9 protein; and
(b) a single molecule DNA-targeting RNA comprising, in 5′ to 3′ order:
(i) a targeter-RNA that hybridizes with a target sequence of the target DNA molecule,
(ii) a nucleotide linker; and
(iii) an activator-RNA that hybridizes with the targeter-RNA to form a double-stranded RNA duplex,
wherein (a) forms a complex with (b) and the target DNA molecule is modified.
2. The method of claim 1 , wherein the target DNA molecule is modified by being cleaved.
3. The method of claim 1 , wherein the method comprises introducing into the cell:
(1) the single molecule DNA-targeting RNA, or a DNA molecule that encodes the single molecule DNA-targeting RNA; and
(2) the Cas9 protein, an RNA molecule that encodes the Cas9 protein, or a DNA molecule that encodes the Cas9 protein.
4. The method of claim 3 , wherein the DNA molecule that encodes the single molecule DNA-targeting RNA and/or the DNA molecule that encodes the Cas9 protein is a recombinant expression vector.
5. The method of claim 3 , wherein the method comprises introducing into the cell a DNA molecule that encodes both the single molecule DNA-targeting RNA and the Cas9 protein.
6. The method of claim 3 , wherein the RNA molecule or the DNA molecule of (2) comprises a nucleotide sequence that is modified relative to a corresponding wild-type nucleotide sequence encoding a Cas9 protein, wherein the modification replaces one or more codons in the wild-type nucleotide sequence with one or more different codons encoding the same amino acid.
7. The method of claim 3 , wherein the method comprises introducing a donor polynucleotide into the cell.
8. The method of claim 3 , wherein the method comprises introducing two or more single molecule DNA-targeting RNAs into the cell, wherein the two or more single molecule DNA-targeting RNAs are complementary to different target sequences within the same or different target DNA molecules.
9. The method of claim 8 , wherein the two or more single molecule DNA-targeting RNAs are introduced into the cell at the same time.
10. The method of claim 1 , wherein said contacting comprises inducing expression of (a) and/or (b).
11. The method of claim 1 , wherein the Cas9 protein comprises one or more mutations in a RuvC domain and/or a HNH domain.
12. The method of claim 1 , wherein:
the targeter-RNA comprises the 12 nucleotide (nt) crRNA sequence GUUUUAGAGCUA (SEQ ID NO: 679),
the nucleotide linker comprises the 4 nt sequence 5′-GAAA-3′, and
the activator-RNA comprises the 67 nt tracrRNA sequence 5′-UAGCAAGUUAAAAUAAGGCUAGUCCGUUAUCAACUUGAAAAAGUGGCACCGAGUC GGUGCUUUUUUU-3′ (SEQ ID NO: 432).
13. The method of claim 1 , wherein (i) comprises the crRNA sequence GUUUUAGAGCUA (SEQ ID NO: 679) and (iii) comprises the tracrRNA sequence 5′-UAGCAAGUUAAAAUAAGGCUAGUCCG-3′ (SEQ ID NO: 397).