Patent ID: 9567594
Date: 2017-02-14
CPC Classifications: C07K,C12N,C12P,C12Y

Claim:
1. A method for site specific incorporation of phosphoserine into a target protein, comprising expressing a messenger RNA (mRNA) encoding the target protein in a system comprising: an O-phosphoseryl-tRNA synthetase (SepRS) that aminoacylates a tRNA (tRNA a tRNA an elongation factor (EF-Sep) comprising: (i) an amino acid sequence at least 90% identical to SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4, wherein the amino acid sequence comprises the amino acids of SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4 at positions corresponding to amino acid number 67, 217, 219, 229, and 274 of SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4, and a substitution mutation corresponding to amino acid number 216 of SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4; or (ii) an amino acid binding pocket for aminoacylated tRNA, wherein the binding pocket comprises the binding pocket for aminoacylated tRNA of SEQ ID NO:3 with an asparagine-to-valine substitution at amino acid residue 216 (N216V) of SEQ ID NO:3; wherein the EF-Sep that binds the Sep-tRNA wherein the SepRS aminoacylates tRNA wherein the EF-Sep binds and protects Sep-tRNA