Selective incorporation of 5-hydroxytryptophan into proteins in mammalian cells
This invention provides methods and compositions for incorporation of an unnatural amino acid into a peptide using an orthogonal aminoacyl tRNA synthetase/tRNA pair. In particular, an orthogonal pair is provided to incorporate 5-hydroxy-L-tryptophan in a position encoded by an opal mutation.
1. A composition comprising an orthogonal aminoacyl tRNA synthetase (O-RS) encoded by a nucleic acid comprising a polynucleotide sequence selected from the group consisting of: SEQ ID NO: 1, a sequence at least 80% identical to SEQ ID NO: 1 and encoding a polypeptide having at least 90% identity to the sequence of SEQ ID NO: 2 comprising a proline residue at a position corresponding to position 144 of SEQ ID NO: 2, or comprising a complementary polynucleotide sequence thereof;
wherein the O-RS preferentially aminoacylates a reference O-tRNA of SEQ ID NO: 3 with 5-hydroxy-L-tryptophan (5-HTPP) or 5-substituted tryptophan analog when the reference O-tRNA 5-hydroxy-L-tryptophan (5-HTPP) or 5-substituted tryptophan analog, and the O-RS are present in a eukaryotic cell.
2. The composition of claim 1 , wherein the O-RS comprises the amino acid sequence SEQ ID NO: 2.
3. The composition of claim 1 , wherein the O-RS comprises one or more improved or enhanced enzymatic properties, selected from the group consisting of:
Km and Kcat, for aminoacylation with the 5-hydroxytryptophan (5-HTPP) as compared to a tryptophan.
4. The composition of claim 1 , further comprising an orthogonal tRNA (O-tRNA) of SEQ. ID NO: 3.
5. The composition of claim 4 , wherein the O-tRNA is not substantially aminoacylated by an endogenous aminoacyl-tRNA synthetase.
6. The composition of claim 4 , wherein the O-tRNA recognizes a selector codon.
7. The composition of claim 6 , wherein the selector codon comprises a sequence selected from the group consisting of: a four base codon, a rare codon, UAG, UGA, and UAA.
8. The composition of claim 1 , further comprising an endogenous translation system.
9. The composition of claim 8 , wherein the endogenous translation system comprises a cell or an in vitro translation system.
10. The composition of claim 9 , wherein the cell comprises mammalian cells.
11. The composition of claim 1 , further comprising a nucleic acid encoding a product peptide.
12. The composition of claim 11 , further comprising an O-tRNA, and the nucleic acid encoding the product peptide comprises a selector codon sequence recognized by the O-tRNA.
13. The composition of claim 11 , wherein the product peptide comprises an amino acid sequence that is at least 75% identical to that of a wild type therapeutic protein, a diagnostic protein, an industrial enzyme, or a portion thereof.