Engineered target specific nucleases

1. An engineered Flavobacterium okeanokoites (FokI) cleavage half-domain, wherein the engineered cleavage half-domain comprises one or more substitution mutations of a wild-type residue of the full length FokI cleavage domain as shown in SEQ ID NO:1, wherein the one or more substitution mutations are as follows:

(i) the wild type Gln (Q) residue at position 481 is replaced with an Ala (A), Cys (C), Asp (D), Ser (S), or Glu (E) residue (Q481A, Q481C, Q481D, Q481S, or Q481E);

(ii) the wild-type Ser (S) residue at position 418 is replaced with a Glu (E) or Asp (D) residue (S418E or S418D);

(iii) the wild-type Ile (I) residue at position 479 is replaced with a Gln (Q) or Thr (T) residue (I479Q or I479T);

(iv) the wild-type Pro (P) residue at position 478 is replaced an Asp (D) residue (P478D);

(v) the wild-type Lys (K) residue at position 525 is replaced with an Ala (A), Cys (C), Glu (E), Ile (I), Ser (S), Thr (T) or Val (V) residue (K525A, K525C, K525E, K252I, K525S, K525T, or K525V);

(vi) the wild-type Arg (R) residue as position 416 is replaced with an Asp (D), Glu (E), His (H) or Asn (N) residue (R416D, R416E, R416H, or R416N);

(vii) the wild-type Gly (G) residue at position 480 is replaced with an Asp (D) residue (G480D);

(viii) the wild-type Ser (S) residue a position 472 is replaced with an Asp (D) residue (S472D);

(ix) the wild-type Asn (N) residue at position 476 is replaced with a Glu (E) residue or a Gly (G) residue (N476E or N476G);

(x) the wild-type Gln (Q) residue at position 531 is replaced with an Arg (R) or Thr (T) residue (Q531R or Q531T);

(xi) the wild-type Arg (R) residue at position 422 is replaced with a His (H) residue (R422H);

(xii) the wild-type Ser (S) residue at position 446 is replaced with an Asp (D) residue (S446D);

(xiii) the wild-type residue at position 448 is replaced with an Ala (A) residue (K448A);

(xiv) the wild-type His (H) residue at position 523 is replaced with a Glu (E) residue (H523E);

(xv) the wild-type Leu (L) residue at position 424 is replaced with a Phe (F) residue (L424F); and/or

(xvi) the wild-type Asn (N) residue at position 542 is replaced with an Asp (D) residue (N542D).

2. The engineered cleavage half-domain of claim 1 , comprising mutations as follows: the R416D, R416E, R416H, or R416N mutation and the R422H mutation; the R416D, R416E, R416H, or R416N mutation and the K448A mutation; the K448A and I479Q mutations; the K448A and Q481A mutations; and/or K448A mutation and the K525A, K525C, K525E, K252I, K525S, K525T, or K525V mutation.

3. The engineered cleavage half-domain of claim 1 , further comprising an additional mutation at one or more of positions 432, 441, 483, 486, 487, 490, 496, 499, 527, 537, 538 and 559.

4. A heterodimer comprising a first engineered cleavage half-domain of claim 1 and a second cleavage half-domain.

5. A heterodimer comprising a first and second engineered cleavage half-domains according to claim 1 .

6. An artificial nuclease comprising an engineered cleavage half-domain of claim 1 , and an engineered DNA-binding domain.

7. An artificial nuclease comprising an engineered cleavage half-domain of claim 3 , and an engineered DNA-binding domain.

8. The artificial nuclease of claim 6 , wherein the engineered DNA-binding domain comprises a zinc finger protein, a TALE-effector domain or a single guide RNA (sgRNA).

9. The artificial nuclease of claim 8 , wherein the zinc finger protein comprises at least three zinc finger DNA-binding domains, wherein each zinc finger DNA-binding domain comprises two beta sheets, an alpha helix, a recognition helix region that binds to a nucleotide sequence, and further wherein one or more of the zinc finger DNA-binding domains comprise mutations in amino acid residues (-5), (-9) and/or (-14), numbered relative to the start of the alpha helix region.

10. The artificial nuclease of claim 7 , wherein the DNA-binding domain comprises a zinc finger protein, a TALE-effector domain or a single guide RNA (sgRNA).

11. The artificial nuclease of claim 10 , wherein the zinc finger protein comprises at least three zinc finger DNA-binding domains, wherein each zinc finger DNA-binding domain comprises two beta sheets, an alpha helix, a recognition helix region that binds to a nucleotide sequence, and further wherein one or more of the zinc finger DNA-binding domains comprise mutations in amino acid residues (-5), (-9) and/or (-14), numbered relative to the start of the alpha helix region.

12. An isolated cell comprising the engineered cleavage half-domain of claim 1 .

13. An isolated cell comprising the engineered cleavage half-domain of claim 3 .

14. A method for cleaving genomic cellular chromatin in a region of interest, the method comprising:

expressing an artificial nuclease according to claim 6 in a cell,

wherein the nuclease site-specifically cleaves a nucleotide sequence in the region of interest of the genomic cellular chromatin.

15. The method of claim 14 , further comprising contacting the cell with a donor polynucleotide; wherein cleavage of the cellular chromatin facilitates homologous recombination between the donor polypeptide and the cellular chromatin.

16. A method of cleaving at least two target sites in genomic cellular chromatin, the method comprising:

cleaving at least first and second target sites in genomic cellular chromatin, wherein each target site is cleaved using a composition comprising an artificial nuclease according to claim 6 .