Nucleic acid binding proteins
View Patent ↗Disclosed herein are methods for designing DNA binding proteins comprising a plurality of zinc fingers and methods for binding the proteins to target nucleotide sequences in cells.
1. A method for binding a nucleic acid binding protein to a target nucleotide sequence, wherein the binding protein comprises a plurality of zinc fingers, and further wherein at least two adjacent zinc fingers bind synergistically to overlapping quadruplet target subsites, wherein the method comprises:
i) selecting a quadruplet within the target nucleotide sequence;
ii) designing the binding protein such that binding of a zinc finger to the quadruplet is obtained by choosing the sequence of particular residues of the zinc finger depending on the nucleotide sequence of the quadruplet, as follows:
a) if base 4 in the quadruplet is G, then position +6 in the α-helix is Arg or Lys;
b) if base 4 in the quadruplet is A, then position +6 in the α-helix is Glu, Asn or Val;
c) if base 4 in the quadruplet is T, then position +6 in the α-helix is Ser, Thr, Val or Lys;
d) if base 4 in the quadruplet is C, then position +6 in the α-helix is Ser, Thr, Val, Ala, Glu or Asn;
e) if base 3 in the quadruplet is G, then position +3 in the α-helix is His;
f) if base 3 in the quadruplet is A, then position +3 in the α-helix is Asn;
g) if base 3 in the quadruplet is T, then position +3 in the α-helix is Ala, Ser or Val;
h) if base 3 in the quadruplet is C, then position +3 in the α-helix is Ser, Asp, Glu, Leu, Thr or Val;
i) if base 2 in the quadruplet is G, then position −1 in the α-helix is Arg;
j) if base 2 in the quadruplet is A, then position −1 in the α-helix is Gln;
k) if base 2 in the quadruplet is T, then position −1 in the α-helix is His or Thr;
l) if base 2 in the quadruplet is C, then position −1 in the α-helix is Asp or His;
m) if base 1 in the quadruplet is G, then position +2 is Glu;
n) if base 1 in the quadruplet is A, then position +2 Arg or Gln;
o) if base 1 in the quadruplet is C, then position +2 is Asn, Gln, Arg, His or Lys;
p) if base 1 in the quadruplet is T, then position +2 is Ser or Thr; and the method comprises
(iii) preparing a nucleic acid encoding the binding protein of (ii); and
(iv) introducing the nucleic acid of (iii) into a cell,
whereby the encoded nucleic acid binding protein is expressed and binds to the target sequence.
2. A method for binding a nucleic acid binding protein to a target sequence, wherein the binding protein comprises a plurality of zinc fingers and further wherein at least two adjacent zinc fingers bind synergistically to overlapping quadruplet target subsites,
wherein the protein was designed by:
i) selecting a quadruplet within the target nucleotide sequence;
ii) designing the binding protein such that binding of a zinc finger to the quadruplet is obtained by choosing the sequence of particular residues of the zinc finger depending on the nucleotide sequence of the quadruplet, as follows:
a) if base 4 in the quadruplet is G, then position +6 in the α-helix is Arg or Lys;
b) if base 4 in the quadruplet is A, then position +6 in the α-helix is Glu, Asn or Val;
c) if base 4 in the quadruplet is T, then position +6 in the α-helix is Ser, Thr, Val or Lys;
d) if base 4 in the quadruplet is C, then position +6 in the α-helix is Ser, Thr, Val, Ala, Glu or Asn;
e) if base 3 in the quadruplet is G, then position +3 in the α-helix is His;
f) if base 3 in the quadruplet is A, then position +3 in the α-helix is Asn;
g) if base 3 in the quadruplet is T, then position +3 in the α-helix is Ala, Ser or Val;
h) if base 3 in the quadruplet is C, then position +3 in the α-helix is Ser, Asp, Glu, Leu, Thr or Val;
i) if base 2 in the quadruplet is G, then position −1 in the α-helix is Arg;
j) if base 2 in the quadruplet is A, then position −1 in the α-helix is Gln;
k) if base 2 in the quadruplet is T, then position −1 in the α-helix is His or Thr;
l) if base 2 in the quadruplet is C, then position −1 in the α-helix is Asp or His;
m) if base 1 in the quadruplet is G, then position +2 is Glu;
n) if base 1 in the quadruplet is A, then position +2 Mg or Gln;
o) if base 1 in the quadruplet is C, then position +2 is Asn, Gln, Arg, His or Lys;
p) if base 1 in the quadruplet is T, then position +2 is Ser or Thr; and the method comprises:
(A) preparing a nucleic acid encoding the binding protein; and
(B) introducing the nucleic acid into a cell, whereby the encoded nucleic acid binding protein is expressed and binds to the target sequence.
3. A method of preparing a pharmaceutical composition comprising a zinc finger protein comprising a plurality of zinc fingers or nucleic acid encoding the same, and further wherein at least two adjacent zinc fingers bind synergistically to overlapping quadruplet target subsites, the method comprising:
(i) selecting a quadruplet within a target nucleotide sequence;
(ii) designing the zinc finger protein such that binding of a zinc finger to the quadruplet is obtained by choosing the sequence of particular residues of the zinc finger depending on the nucleotide sequence of the quadruplet, as follows:
a) if base 4 in the quadruplet is G, then position 6 in the α-helix is Arg or Lys;
b) if base 4 in the quadruplet is A, then position 6 in the α-helix is Glu, Asn or Val;
c) if base 4 in the quadruplet is T, then position +6 in the α-helix is Ser, Thr, Val or Lys;
d) if base 4 in the quadruplet is C, then position +6 in the α-helix is Ser, Thr, Val, Ala, Glu or Asn;
e) if base 3 in the quadruplet is G, then position +3 in the α-helix is His;
f) if base 3 in the quadruplet is A, then position +3 in the α-helix is Asn;
g) if base 3 in the quadruplet is T, then position +3 in the α-helix is Ala, Ser or Val;
h) if base 3 in the quadruplet is C, then position +3 in the α-helix is Ser, Asp, Glu, Leu, Thr or Val;
i) if base 2 in the quadruplet is G, then position −1 in the α-helix is Arg;
j) if base 2 in the quadruplet is A, then position −1 in the α-helix is Gln;
k) if base 2 in the quadruplet is T, then position −1 in the α-helix is His or Thr;
l) if base 2 in the quadruplet is C, then position −1 in the α-helix is Asp or His;
m) if base 1 in the quadruplet is G, then position +2 is Glu;
n) if base 1 in the quadruplet is A, then position +2 Arg or Gln;
o) if base 1 in the quadruplet is C, then position +2 is Asn, Gln, Arg, His or Lys;
p) if base 1 in the quadruplet is T, then position +2 is Ser or Thr; and the method comprises
(iii) preparing the zinc finger protein or a nucleic acid encoding the zinc finger protein; and
(iv) incorporating the zinc finger protein or the nucleic acid encoding the zinc finger protein into a phannaceutical composition.
4. The method of claim 3 , wherein the zinc finger protein is a component of a fusion protein.
5. A method of preparing a pharmaceutical composition comprising a zinc finger protein comprising a plurality of zinc fingers or nucleic acid encoding the same, and further wherein at least two adjacent zinc fingers bind synergistically to overlapping quadruplet target subsites, wherein the zinc finger protein was designed by:
(i) selecting a quadruplet within a target nucleotide sequence;
(ii) designing the zinc finger protein such that binding of a zinc finger to the quadruplet is obtained by choosing the sequence of particular residues of the zinc finger depending on the nucleotide sequence of the quadruplet, as follows:
a) if base 4 in the quadruplet is G, then position +6 in the α-helix is Arg or Lys;
b) if base 4 in the quadruplet is A, then position +6 in the α-helix is Glu, Asn or Val;
c) if base 4 in the quadruplet is T, then position +6 in the α-helix is Ser, Thr, Val or Lys;
d) if base 4 in the quadruplet is C, then position +6 in the α-helix is Ser, Thr, Val, Ala, Glu or Asn;
e) if base 3 in the quadruplet is G, then position +3 in the α-helix is His;
f) if base 3 in the quadruplet is A, then position +3 in the α-helix is Asn;
g) if base 3 in the quadruplet is T, then position +3 in the α-helix is Ala, Ser or Val;
h) if base 3 in the quadruplet is C, then position +3 in the α-helix is Ser, Asp, Glu, Leu, Thr or Val;
i) if base 2 in the quadruplet is G, then position −1 in the α-helix is Arg;
j) if base 2 in the quadruplet is A, then position −1 in the α-helix is Gln;
k) if base 2 in the quadruplet is T, then position −1 in the α-helix is His or Thr;
l) if base 2 in the quadruplet is C, then position −1 in the α-helix is Asp or His;
m) if base 1 in the quadruplet is G, then position +2 is Glu;
n) if base 1 in the quadruplet is A, then position +2 Arg or Gln;
o) if base 1 in the quadruplet is C, then position +2 is Asn, Gln, Arg, His or Lys;
p) if base 1 in the quadruplet is T, then position +2 is Ser or Thr; and the method comprises:
(A) preparing the zinc finger protein or a nucleic acid encoding the zinc finger protein; and
(B) incorporating the zinc finger protein or nucleic acid encoding the zinc finger protein into a pharmaceutical composition.
6. The method of claim 5 , wherein the zinc finger protein is a component of a fusion protein.
7. A method according to claim 1 , wherein each zinc finger has the general primary structure
(SEQ ID NO:3)
X a -Cys-X 2–4 -Cys-X 2–3 -Phe- X c -X-X-X-X-Leu-X-X-His-X-X- X b -His/Cys-linker
−1 1 2 3 4 5 6 7 8 9
wherein X (including X a , X b and X c ) is any amino acid.
8. A method according to claim 1 comprising the additional steps of subjecting the nucleic acid binding protein to one or more rounds of randomization and selection in order to improve the characteristics thereof.
9. A method according to claim 8 , wherein the randomization and selection is carried out by phage display technology.
10. A method according to claim 9 , comprising the steps of:
a) preparing a nucleic acid construct which express a fusion protein comprising the nucleic acid binding protein and a minor coat protein of a filamentous bacteriophage;
b) preparing further nucleic acid constructs which express a fusion protein comprising a selectively mutated nucleic acid binding protein and a minor coat protein of a filamentous bacteriophage;
c) causing the fusion proteins defined in steps (a) and (b) to be expressed on the surface of bacteriophage transformed with the nucleic acid constructs;
d) assaying the ability of the bacteriophage to bind the target nucleic acid sequence and selecting the bacteriophage demonstrating superior binding characteristics.
11. A method according to claim 8 , wherein the nucleic acid binding protein is selectively randomized at any one of positions +1, +5, +8, −1, +2, +3 or +6.
12. A method according to claim 11 , wherein, in the nucleic acid binding protein, position +6 of a zinc finger and positions −1, +1, +2 and +3 of an adjacent zinc finger are randomized.
13. A method according to claim 1 , wherein the binding protein further comprises a nucleic acid cleaving domain.
14. A method according to claim 2 , wherein the binding protein further comprises a nucleic acid cleaving domain.
15. A method according to claim 3 , wherein the binding protein further comprises a nucleic acid cleaving domain.
16. A method according to claim 5 , wherein the binding protein further comprises a nucleic acid cleaving domain.