Protein pores
The present invention relates to novel protein pores and their uses in analyte detection and characterisation. The invention particularly relates to an isolated pore complex formed by a CsgG-like pore and a modified CsgF peptide, or a homologue or mutant thereof, thereby incorporating an additional channel constriction or reader head in the nanopore. The invention further relates to a transmembrane pore complex and methods for production of the pore complex and for use in molecular sensing and nucleic acid sequencing applications.
1. A pore comprising a CsgG pore and a modified CsgF peptide, wherein the modified CsgF peptide is bound to CsgG and forms a constriction in the pore, wherein the modified CsgF peptide is a truncated CsgF peptide lacking the C-terminal head domain of CsgF and at least part of the neck domain of CsgF, and wherein the CsgF peptide comprises one or more amino acid substitutions.
2. The pore according to claim 1 , wherein the CsgF peptide:
(i) has a length of from 25 to 45 amino acids;
(ii) comprises the amino acid sequence of SEQ ID NO: 6 from residue 1 up to any one of residues 28 to 45 of SEQ ID NO: 6;
(iii) comprises SEQ ID NO: 39 (residues 1 to 29 of SEQ ID NO: 6);
(iv) comprises SEQ ID NO: 15 (residues 1 to 34 of SEQ ID NO: 6);
(v) comprises SEQ ID NO: 40 (residues 1 to 45 of SEQ ID NO: 6;
(vi) comprises SEQ ID NO: 54 (residues 1 to 30 of SEQ ID NO: 6);
(vii) comprises SEQ ID NO: 55 (residues 1 to 35 of SEQ ID NO: 6).
3. The pore according to claim 1 , wherein the CsgF peptide comprises a modification at one or more of the following positions: G1, T4, F5, R8, N9, N11, F12, A26, Q29, N15, N17, A20, N24, A28 and D34.
4. The pore according to claim 1 , wherein the CsgF peptide comprises one or more of the substitutions: N15S/A/T/Q/G/L/V/I/F/Y/W/R/K/D/C, N17S/A/T/Q/G/L/V/I/F/Y/W/R/K/D/C, A20S/T/Q/N/G/L/V/I/F/Y/W/R/K/D/C, N24S/T/Q/A/G/L/V/I/F/Y/W/R/K/D/C, A28S/T/Q/N/G/L/V/I/F/Y/W/R/K/D/C, D34F/Y/W/R/K/N/Q/C, G1C, T4C, N17S, and D34Y or D34N.
5. The pore according to claim 1 , wherein the CsgG pore comprises from 6 to 10 CsgG monomers.
6. The pore according to claim 1 , wherein the CsgF peptide and the CsgG pore are covalently coupled and the covalent coupling is via:
(i) a cysteine residue at a position corresponding to 132, 133, 136, 138, 140, 142, 144, 145, 147, 149, 151, 153, 155, 183, 185, 187, 189, 191, 201, 203, 205, 207 or 209 of SEQ ID NO: 3,
(ii) a non-native reactive or photoreactive amino acid at a position corresponding to 132, 133, 136, 138, 140, 142, 144, 145, 147, 149, 151, 153, 155, 183, 185, 187, 189, 191, 201, 203, 205, 207 or 209 of SEQ ID NO: 3,
(iii) residues at a position corresponding to one or more of the following pairs of positions of SEQ ID NO: 6 and SEQ ID NO: 3, respectively: 1 and 153, 4 and 133, 5 and 136, 8 and 187, 8 and 203, 9 and 203, 11 and 142, 11 and 201, 12 and 149, 12 and 203, 26 and 191, and 29 and 144, or
(iv) a disulphide bond or click chemistry.
7. The pore according to claim 1 , wherein the interaction between the CsgF peptide and the CsgG pore is stabilised by hydrophobic interactions, electrostatic or covalent interactions at a position corresponding to one or more of the following pairs of positions of SEQ ID NO: 6 and SEQ ID NO: 3, respectively: 1 and 153, 4 and 133, 5 and 136, 8 and 187, 8 and 203, 9 and 203, 11 and 142, 11 and 201, 12 and 149, 12 and 203, 26 and 191, and 29 and 144.
8. The pore according to claim 1 , wherein the CsgG pore comprises at least one monomer comprising one or more modification corresponding to the following modifications in SEQ ID NO:3:
(i) a modification at one or more positions Y51, N55 and F56;
(ii) at least one substitution selected from R97W or R97Y and R93W or R93Y;
(iii) deletion of V105, A106 and 1107 of SEQ ID NO:3;
(iv) deletion of one or more of positions R192, F193, 1194, D105, Y196, Q197, R198, L199 and E201 of SEQ ID NO:3;
(v) at least one substitution selected from K94N/Q/R/F/Y/W/L/S, D43S, E44S, F48S/N/Q/Y/W/I/V/H/R/K, Q87N/R/K, N91K/R, R97F/Y/W/V/I/K/S/Q/H, E101I/L/A/H, N102K/Q/L/I/V/S/H, R110F/G/N, Q114R/K, R142Q/S, T150Y/A/V/L/S/Q/N;
(vi) a modification at one or more of positions 141, R93, A98, Q100, G103, T104, A106, I107, N108, L113, S115, T117, Y130, K135, E170, S208, D233, D238, E244, Q42, E44, L90, N91, N195, A99, E101 and Q114;
(vii) at least one substitution selected from Y51A/I/V/S/T, N55A/I/V/S/T and F56/A/I/V/S/T/Q;
(viii) the substitution R97W;
(ix) deletion of F193, 1194, D195, Y196, Q197, R198 and L199 or deletion of D195, Y196, Q197, R198 and L199;
(x) deletion of V105, A106 and 1107;
(xi) a substitution selected from K94Q and K94N;
(xii) at least one substitution selected from Q42K or Q42R; E44N or E44Q; L90R or L90K; N91R or N91K; I95R or I95K; A99R or A99K; E101H, E101K, E101N, E101Q or E101T; and/or Q114K;
(xiii) the substitution N55V; and/or
(xiv) R or K at a position corresponding to R192.
9. The pore according to claim 1 , which is a double pore comprising two CsgG pores, wherein the modified CsgF peptide is inserted into the lumen of at least one of the CsgG pores.
10. The pore according to claim 2 , wherein one or more of the residues in SEQ ID NO: 15, SEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO: 54, or SEQ ID NO: 55 are modified.
11. The pore according to claim 3 , wherein the modification is the introduction of a cysteine, a hydrophobic amino acid, a charged amino acid, a non-native reactive amino acid, or a photoreactive amino acid.
12. The pore according to claim 5 , wherein the ratio of CsgG monomers to truncated CsgF peptides in the pore is 1:1.