Unnatural reactive amino acid genetic code additions
This invention provides compositions and methods for producing translational components that expand the number of genetically encoded amino acids in eukaryotic cells. The components include orthogonal tRNAs, orthogonal aminoacyl-tRNA synthetases, pairs of tRNAs/synthetases and unnatural amino acids. Proteins and methods of producing proteins with unnatural amino acids in eukaryotic cells are also provided.
1. A composition comprising a protein, wherein the protein comprises at least one unnatural amino acid incorporated site-specifically into the protein using an orthogonal translation system, and at least one site-specific post-translational modification, wherein the at least one site-specific post-translational modification comprises attachment of a molecule comprising a second reactive group by a [3+2]cycloaddition in vivo in a eukaryotic cell to the at least one unnatural amino acid comprising a first reactive group; and
wherein the at least one unnatural amino acid is incorporated site-specifically at any site other than a lysine or cysteine site in the protein.
2. The composition of claim 1 , wherein the molecule is a dye, a polymer, a derivative of polyethylene glycol, a photocrosslinker, a cytotoxic compound, an affinity label, a derivative of biotin, a resin, a second protein or polypeptide, a metal chelator, a cofactor, a fatty acid, a carbohydrate, or a polynucleotide.
3. The composition of claim 1 , wherein the first reactive group is an alkynyl or azido moiety and the second reactive group is an azido or alkynyl moiety.
4. The composition of claim 3 , wherein first reactive group is the alkynyl moiety and the second reactive group is the azido moiety.
5. The composition of claim 4 , wherein the unnatural amino acid comprises a p-propargyloxyphenylalanine.
6. The composition of claim 3 , wherein the first reactive group is the azido moiety and the second reactive group is the alkynyl moiety.
7. The composition of claim 6 , wherein the unnatural amino acid comprises a p-azido-L-phenylalanine.
8. A protein comprising an unnatural amino acid having the chemical structure:
wherein the unnatural amino acid is incorporated site-specifically at any site other than a lysine or cysteine site in the protein.
9. A protein comprising an azido dye having the structure:
or
wherein the azido dye is incorporated site-specifically at any site other than a lysine or cysteine site in the protein.
10. The protein of claim 9 , further comprising at least one unnatural amino acid, wherein the azido dye is attached to the unnatural amino acid through a [3+2]cycloaddition.
11. The protein of claim 10 , wherein the unnatural amino acid comprises an alkynyl amino acid.
12. A protein comprising an alkynyl polyethylene glycol having the structure:
wherein n is an integer between 100 and 2,000, and
wherein the alkynyl polyethylene glycol is incorporated site-specifically at any site other than a lysine or cysteine site in the protein.
13. The protein of claim 12 , further comprising at least one unnatural amino acid, wherein the alkynyl polyethylene glycol is attached to an unnatural amino acid through a [3+2]cycloaddition.
14. The protein of claim 13 , wherein the unnatural amino acid comprises an azido amino acid.
15. A protein produced by growing, in an appropriate medium, a eukaryotic cell that comprises a nucleic acid that comprises at least one selector codon and encodes the protein; wherein the medium comprises an unnatural amino acid and the eukaryotic cell comprises an orthogonal tRNA (O-tRNA) that functions in the cell and recognizes the selector codon and an orthogonal aminoacyl tRNA synthetase (O-RS) that preferentially aminoacylates the O-tRNA with the unnatural amino acid;
incorporating into the protein the unnatural amino acid in the eukaryotic cell, wherein the unnatural amino acid comprises a first reactive group, and
wherein the unnatural amino acid is incorporated site-specifically at any site other than a lysine or cysteine site in the protein; and
contacting the protein with a molecule that comprises a second reactive group; wherein the first reactive group reacts with the second reactive group to attach the molecule to the unnatural amino acid through a [3+2]cycloaddition.
16. The protein of claim 15 , wherein the protein is modified by at least one post-translational modification in vivo and wherein the post-translational modification is selected from the group consisting of: N-glycosylation, O-glycosylation, acetylation, acylation, lipid-modification, palmitoylation, palmitate addition, phosphorylation, and glycolipid-linkage modification.