Proteins and peptide tags with enhanced rate of spontaneous isopeptide bond formation and uses thereof

1. A two-part linker comprising a peptide and a polypeptide, wherein:

a) said peptide comprises an amino acid sequence as set forth in SEQ ID NO: 1, wherein:

(i) X at position 1 is arginine or no amino acid;

(ii) X at position 2 is glycine or no amino acid;

(iii) X at position 5 is histidine or threonine;

(iv) X at position 11 is alanine, glycine or valine; and

(v) X at position 14 is arginine or lysine,

wherein when X at position 1 is no amino acid, X at position 2 is no amino acid; and

b) said polypeptide comprises:

i) an amino acid sequence as set forth in SEQ ID NO: 2;

ii) a portion of (i) comprising an amino acid sequence as set forth in SEQ ID NO: 101;

iii) an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and one or more of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) aspartic acid at position 100:

7) glutamic acid at position 108; and

8) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2; or

iv) a portion of (iii) comprising an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 101, wherein the amino acid sequence comprises a lysine at position 10, a glutamic acid at position 56 and one or more of the following:

1) arginine at position 16;

2) histidine at position 41;

3) proline at position 68; and

4) aspartic acid at position 76,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 101, and wherein said peptide and polypeptide are capable of spontaneously forming an isopeptide bond between the aspartic acid residue at position 10 of SEQ ID NO: 1 and the lysine residue at position 34 of SEQ ID NO: 2 or position 10 of SEQ ID NO: 101.

2. The two-part linker of claim 1 , wherein the peptide comprises one or more of the following:

1) histidine at position 5;

2) alanine at position 11; and

3) arginine at position 14.

3. The two-part linker of claim 1 , wherein the peptide comprises an amino acid sequence as set forth in any one of SEQ ID NOs: 3-5.

4. The two-part linker of claim 1 , wherein the polypeptide comprises an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and all of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) glutamic acid at position 108; and

6) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2.

5. The two-part linker of claim 1 , wherein the polypeptide comprises an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and all of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) glutamic acid at position 108; and

7) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2.

6. The two-part linker of claim 1 , wherein the polypeptide comprises an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and all of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) aspartic acid at position 100:

7) glutamic acid at position 108; and

8) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2.

7. The two-part linker of claim 1 , wherein the polypeptide comprises one or more of the following:

1) glycine at position 12; and

2) threonine at position 22,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2.

8. The two-part linker of claim 1 , wherein said peptide and/or said polypeptide is conjugated to a nucleic acid molecule, protein, peptide, small-molecule organic compound, fluorophore, metal-ligand complex, polysaccharide, nanoparticle, nanotube, polymer, cell, virus, virus-like particle or a combination thereof.

9. The two-part linker of claim 1 , wherein the peptide and/or polypeptide is immobilised on a solid substrate.

10. A peptide capable of spontaneously forming an isopeptide bond with a polypeptide comprising an amino acid sequence as set forth in SEQ ID NO: 2, said peptide comprising an amino acid sequence as set forth in SEQ ID NO: 1, wherein:

(i) X at position 1 is arginine or no amino acid;

(ii) X at position 2 is glycine or no amino acid;

(iii) X at position 5 is histidine or threonine;

(iv) X at position 11 is alanine, glycine or valine; and

(v) X at position 14 is arginine or lysine,

wherein when X at position 1 is no amino acid, X at position 2 is no amino acid,

and wherein said isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 1 and the lysine residue at position 34 of SEQ ID NO: 2.

11. The peptide of claim 10 , wherein the peptide comprises one or more of the following:

1) histidine at position 5;

2) alanine at position 11; and

3) arginine at position 14.

12. A polypeptide comprising:

i) an amino acid sequence as set forth in SEQ ID NO: 2; or

ii) a portion of (i) comprising an amino acid sequence as set forth in SEQ ID NO: 101; or

iii) an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and two or more of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) aspartic acid at position 100:

7) glutamic acid at position 108; and

8) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2; or

iv) a portion of (iii) comprising an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 101, wherein the amino acid sequence comprises a lysine at position 10, a glutamic acid at position 56 and or more of the following:

1) arginine at position 16;

2) histidine at position 41;

3) proline at position 68; and

4) aspartic acid at position 76,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 101, and wherein said polypeptide is capable of spontaneously forming an isopeptide bond with a peptide comprising an amino acid sequence as set forth in SEQ ID NO: 5, wherein said isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 5 and the lysine residue at position 34 of SEQ ID NO: 2 or position 10 of SEQ ID NO: 101.

13. The polypeptide of claim 12 , wherein the polypeptide comprises an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and all of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) glutamic acid at position 108; and

6) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2.

14. A process for conjugating two molecules or components via an isopeptide bond comprising:

a) providing a first molecule or component comprising a peptide capable of spontaneously forming an isopeptide bond with a polypeptide comprising an amino acid sequence as set forth in SEQ ID NO: 2, the peptide comprising an amino acid sequence as set forth in SEQ ID NO: 1, wherein:

(i) X at position 1 is arginine or no amino acid;

(ii) X at position 2 is glycine or no amino acid;

(iii) X at position 5 is histidine or threonine;

(iv) X at position 11 is alanine, glycine or valine; and

(v) X at position 14 is arginine or lysine,

wherein when X at position 1 is no amino acid, X at position 2 is also no amino acid,

and wherein isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 1 and the lysine residue at position 34 of SEQ ID NO: 2;

b) providing a second molecule or component comprising a polypeptide, the polypeptide comprising:

i) an amino acid sequence as set forth in SEQ ID NO: 2; or

ii) a portion of (i) comprising an amino acid sequence as set forth in SEQ ID NO: 101; or

iii) an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and one or more of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) aspartic acid at position 100:

7) glutamic acid at position 108; and

8) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2; or

iv) a portion of (iii) comprising an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 101, wherein the amino acid sequence comprises a lysine at position 10, a glutamic acid at position 56 and one or more of the following:

1) arginine at position 16;

2) histidine at position 41;

3) proline at position 68; and

4) aspartic acid at position 76,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 101, and wherein said polypeptide is capable of spontaneously forming an isopeptide bond with a peptide comprising an amino acid sequence as set forth in SEQ ID NO: 5, wherein said isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 5 and the lysine residue at position 34 of SEQ ID NO: 2 or position 10 of SEQ ID NO: 101;

c) contacting said first and second molecules or components under conditions that enable the spontaneous formation of an isopeptide bond between the peptide and polypeptide, thereby conjugating said first molecule or component to said second molecule or component via an isopeptide bond to form a complex.

15. A kit, wherein said kit comprises:

(a) a peptide capable of spontaneously forming an isopeptide bond with a polypeptide comprising an amino acid sequence as set forth in SEQ ID NO: 2, optionally conjugated or fused to a molecule or component, the peptide comprising an amino acid sequence as set forth in SEQ ID NO: 1, wherein:

(i) X at position 1 is arginine or-no amino acid;

(ii) X at position 2 is glycine or no amino acid;

(iii) X at position 5 is histidine or threonine;

(iv) X at position 11 is alanine, glycine or valine; and

(v) X at position 14 is arginine or lysine,

wherein when X at position 1 is no amino acid, X at position 2 is also no amino acid,

and wherein said isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 1 and the lysine residue at position 34 of SEQ ID NO: 2; and

(b) a polypeptide, optionally conjugated or fused to a molecule or component, the polypeptide comprising:

i) an amino acid sequence as set forth in SEQ ID NO: 2; or

ii) a portion of (i) comprising an amino acid sequence as set forth in SEQ ID NO: 101; or

iii) an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 2, wherein said amino acid sequence comprises a lysine at position 34, a glutamic acid at position 80 and one or more of the following:

1) threonine at position 5;

2) proline at position 16;

3) arginine at position 40;

4) histidine at position 65;

5) proline at position 92;

6) aspartic acid at position 100:

7) glutamic acid at position 108; and

8) threonine at position 116,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 2; or

iv) a portion of (iii) comprising an amino acid sequence with at least 80% sequence identity to a sequence as set forth in SEQ ID NO: 101, wherein the amino acid sequence comprises a lysine at position 10, a glutamic acid at position 56 and one or more of the following:

1) arginine at position 16;

2) histidine at position 41;

3) proline at position 68; and

4) aspartic acid at position 76,

wherein the specified amino acid residues are at positions equivalent to the positions in SEQ ID NO: 101, and wherein said polypeptide is capable of spontaneously forming an isopeptide bond with a peptide comprising an amino acid sequence as set forth in SEQ ID NO: 5, wherein said isopeptide bond forms between the aspartic acid residue at position 10 of SEQ ID NO: 5 and the lysine residue at position 34 of SEQ ID NO: 2 or position 10 of SEQ ID NO: 101; and/or

(c) a nucleic acid molecule, encoding a peptide as defined in (a); and

(d) a nucleic acid molecule, encoding a polypeptide as defined in (b).

16. The peptide of claim 10 , wherein said peptide is conjugated to a nucleic acid molecule, protein, peptide, small-molecule organic compound, fluorophore, metal-ligand complex, polysaccharide, nanoparticle, nanotube, polymer, cell, virus, virus-like particle or a combination thereof.

17. The peptide of claim 10 , wherein said peptide comprises an amino acid sequence as set forth in any one of SEQ ID NOs: 3-5.

18. The polypeptide of claim 12 , wherein said polypeptide is conjugated to a nucleic acid molecule, protein, peptide, small-molecule organic compound, fluorophore, metal-ligand complex, polysaccharide, nanoparticle, nanotube, polymer, cell, virus, virus-like particle or a combination thereof.