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, the method comprising:
contacting a target DNA molecule having a target sequence with a complex comprising:
(a) a Cas9 protein; and
(b) a DNA-targeting RNA comprising:
(i) a targeter-RNA that hybridizes with the target sequence, and
(ii) an activator-RNA that hybridizes with the targeter-RNA to form a double-stranded RNA (dsRNA) duplex of a protein-binding segment,
wherein the activator-RNA hybridizes with the targeter-RNA to form a total of 10 to 15 base pairs,
wherein said contacting takes place outside of a bacterial cell and outside of an archaeal cell,
thereby resulting in modification of the target DNA molecule.
2. The method of claim 1 , wherein said modification of the target DNA molecule is cleavage of the target DNA molecule.
3. The method of claim 1 , wherein the target sequence is 15 nucleotides (nt) to 18 nt long.
4. The method of claim 1 , wherein the target sequence is 18 nucleotides (nt) to 25 nt long.
5. The method of claim 1 , wherein the target DNA molecule is chromosomal DNA.
6. The method of claim 1 , wherein the activator-RNA comprises the 26 nucleotide tracrRNA sequence set forth in SEQ ID NO: 441.
7. The method of claim 1 , wherein the targeter-RNA and/or the activator-RNA comprises one or more of: a non-natural internucleoside linkage, a nucleic acid mimetic, a modified sugar moiety, and a modified nucleobase.
8. The method of claim 1 , wherein the targeter-RNA and/or the activator-RNA comprises one or more of: (i) a non-natural internucleoside linkage selected from a phosphorothioate, an inverted polarity linkage, and an abasic nucleoside linkage; (ii) a locked nucleic acid (LNA); and (iii) a modified sugar moiety selected from 2′-O-methoxyethyl, 2′-O-methyl, and 2′-fluoro.
9. The method of claim 1 , wherein the targeter-RNA and/or the activator-RNA comprises one or more of: a peptide nucleic acid (PNA), a morpholino nucleic acid, a cyclohexenyl nucleic acid (CeNA), and/or a locked nucleic acid (LNA).
10. The method of claim 1 , wherein the targeter-RNA and/or the activator-RNA comprises one or more modified sugar moieties selected from: 2′-O-(2-methoxyethyl), 2′-dimethylaminooxyethoxy, 2′-dimethylaminoethoxyethoxy, 2′-O-methyl, and 2′-fluoro.
11. The method of claim 1 , wherein the targeter-RNA and/or the activator-RNA is conjugated to a moiety selected from: a polyamine; a polyamide; a polyethylene glycol; a polyether; a cholesterol moiety; a cholic acid; a thioether; a thiocholesterol; an aliphatic chain; a phospholipid; an adamantane acetic acid; a palmityl moiety; an octadecylamine or hexylamino-carbonyl-oxycholesterol moiety; a biotin; a phenazine; a folate; a phenanthridine; an anthraquinone; an acridine; a fluorescein; a rhodamine; a fluor; and a coumarin.