Patent ID: 7824893

Claim:
A eubacterial cell comprising a first orthogonal aminoacyl-tRNA synthetase (O-RS) that functions in the cell, wherein the O-RS preferentially aminoacylates a first orthogonal tRNA (O-tRNA) with a first unnatural amino acid that is an alkynyl amino acid; wherein said first O-RS is at least 90% identical to the wild-type Methanococcus jannaschii tyrosyl-tRNA synthetase having the amino acid sequence of SEQ ID NO: 2, wherein the O-RS has an amino acid sequence comprising: (a) alanine at amino acid position 32; (b) alanine or Leu at amino acid position 158; and (c) alanine or proline at amino acid position 162; and, wherein the alkynyl amino acid is a para-substituted tyrosine or a para-substituted phenylalanine.