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 method of reacting a peptide comprising a 5-hydroxy-L-tryptophan (5-HTPP) with a molecule reactive with 5-HTPP, the method comprising:
providing a peptide comprising one or more unnatural amino acids wherein at least one of the unnatural amino acids is 5-hydroxy-L-tryptophan (5-HTPP),
providing a reactive molecule reactive with the 5-HTPP; and,
reacting the reactive molecule covalently with the 5-HTPP, wherein said providing the peptide comprises:
i) preparing a construct comprising a nucleic acid sequence encoding an orthogonal tRNA synthetase (O-RS) and comprising at least 90% identity to the sequence of SEQ ID NO: 2, the O-RS comprising a proline residue at a position corresponding to position 144 of SEQ ID NO: 2, wherein the O-RS aminoacylates a reference orthogonal tRNA (O-tRNA) of SEQ ID NO: 3 with a 5-HTPP when the reference O-tRNA, 5-HTPP, and the O-RS are present in a eukaryotic cell;
ii) preparing a construct comprising a nucleic acid sequence encoding an O-tRNA comprising: at least 90% identity to SEQ ID NO: 3, wherein the O-tRNA is aminoacylated with a 5-HTPP by a reference O-RS of SEQ ID NO: 2 when the reference O-RS, 5-HTPP, and the O-tRNA are present in a eukaryotic cell;
iii) introducing the O-RS construct and the O-tRNA construct into the eukaryotic cell; and,
iv) preferentially aminoacylating an expressed O-tRNA with the 5-HTPP, wherein said aminoacylation is catalyzed by an expressed O-RS, wherein the O-tRNA recognizes a selector codon in a nucleic acid sequence encoding the peptide, whereby the 5-HTPP is incorporated into the peptide in the eukaryotic cell.
2. The method of claim 1 , further comprising applying a voltage to the peptide, thereby reacting the 5-HTPP with the reactive molecule.
3. The method of claim 1 , wherein reacting comprises cross-linking.
4. The method of claim 1 , wherein the reactive molecule comprises an unnatural amino acid in another peptide.
5. The method of claim 4 , wherein the amino acid on another peptide is selected from the group consisting of: 5-HTPP and cysteine.
6. The method of claim 1 , further comprising detecting an interaction between the peptide and another peptide.
7. The method of claim 6 , wherein said detecting comprises fluoroscopy.