Expanding the scope of protein biosynthesis by altering the methionyl- tRNA synthetase activity of a bacterial expression host

The incorporation of amino acids into proteins in vivo is controlled by the amino-acyl-tRNA synthetases. The successful incorporation of a nonnatural amino acid, trans-crotylglycine (Tcg), into a protein has now been achieved by increasing the methionyl-tRNA synthetase activity of a bacterial expression host (see scheme). The incorporation of Tcg into proteins creates new opportunities for macromolecular synthesis through genetic engineering, due to the rich chemistry of the olefinic side chain.