Disulfide stabilized foldon polypeptides
Intermolecular disulfide stabilized foldon polypeptides are provided.
1. A cysteine-substituted foldon polypeptide, wherein two amino acids of a native foldon polypeptide are substituted with cysteine residues that can form intermolecular disulfide bonds when the foldon is in a trimeric quaternary structure, wherein the native foldon polypeptide has the amino acid sequence set forth in SEQ ID NO:1 and wherein the amino acid substitutions are selected from [G10C, D17C]; [R8C, D17C]; [R8C, G18C]; [P7C, G18C]; [A12C, K16C]; and [Y13C, R15C].
2. The cysteine-substituted foldon polypeptide of claim 1 , wherein the amino acid substitutions are selected from [A12C, K16C]; [R8C, D17C]; and [R8C, G18C].
3. The cysteine-substituted foldon polypeptide of claim 1 , wherein the cysteine-substituted foldon polypeptide is a monomer.
4. The cysteine-substituted foldon polypeptide of claim 1 , wherein the cysteine-substituted foldon polypeptide is a trimer.
5. The cysteine-substituted foldon polypeptide of claim 1 , wherein the cysteine-substituted foldon polypeptide is joined to a fusion partner.
6. The cysteine-substituted foldon polypeptide of claim 5 , wherein the fusion partner is a viral antigen.
7. The cysteine-substituted foldon polypeptide of claim 1 , further comprising one or more of a tag for purification, an unnatural amino acid, and site for protease cleavage.
8. The cysteine-substituted foldon polypeptide of claim 7 , wherein the cysteine-substituted foldon polypeptide is a fusion protein, and comprises at least one unnatural amino acid at a defined site.
9. The cysteine-substituted foldon polypeptide of claim 8 , where the cysteine-substituted foldon polypeptide is a trimer, and the unnatural amino acid is used to covalently join one chain of the trimer to a virus like particle.
10. A method of producing a cysteine-substituted foldon polypeptide according to claim 1 , comprising introducing a polynucleotide sequence encoding the cysteine-substituted foldon polypeptide operably linked to a promoter, into a cell or cell free protein synthesis reaction mix and incubating for a period of time sufficient to synthesize the protein.