Patent ID: 7575895

Claim:
A translation system comprising: an orthogonal lysyl tRNA (lysyl O-tRNA) comprising SEQ ID NO: 24; and an orthogonal Pyrococcus horikoshil aminoacyl tRNA synthetase (O-RS) variant comprising a glutamic acid to glycine mutation at position 444 (PhE444G) (SEQ ID NO: 30), or conservative variants displaying at least 95% identity to SEQ ID NO: 30 that comprise a glycine residue at a site corresponding to amino acid 444 of PhE444G, wherein the O-RS preferentially charges the lysyl O-tRNA of SEQ ID NO: 24 with one or more amino acids and wherein the O-RS displays reduced toxicity when expressed in E. coli as compared to the synthetase from Pyrococcus horikoshii which synthetase comprises SEQ ID NO: 30 except for the presence of a glutamic acid residue at position 444.