Engineering the Translation Apparatus to Incorporate Nonnatural Amino Acids

Abstract

Incorporation of nonnatural amino acids into proteins has exerted great effects on many fields. In recent years, the engineering of translation apparatus facilitates the boom of this field. The modifications on tRNAs, tRNA synthetases, ribosomes, elongation factors and release factors efficiently broaden the repertoire of amino acids and largely increase the efficiency of incorporation. In addition, deep understanding of the translation mechanism helps us generate certain kinds of RNAs which can act as alternative translation components to catalyze the aminoacylation step or inhibitors to attenuate the activity of a certain component. Here I review the strategies to evolve or engineer the components of translation apparatus as well as the methods to control their activity to meet our needs.

Functionalizing Nanoparticles with Biological Molecules: Developing Chemistries that Facilitate Nanotechnology

“…Semisynthetic methods rely primarily on chemoselectively modifying proteins and other peptides to accomplish the insertion . In contrast, recombinant methods usually require more complex strategies for modifying codons along with tRNAs and some of the requisite expression enzymes in auxotrophic Escherichia coli strains. − Codons for phenylalanine, leucine, isoleucine, proline, tryptophan, and methionine have all been “reassigned” to allow non-natural amino acid incorporation. Methionine, in particular, is the most frequently targeted because it is among the rarest of amino acids found in proteins.…”

“…Methionine, in particular, is the most frequently targeted because it is among the rarest of amino acids found in proteins. Incorporation is further facilitated by overexpression of the appropriate tRNA transferase in conjunction with simultaneous relaxation of its proofreading and substrate specificity. − Figure highlights the structure of several such amino acids along with the potentially reactive or functional groups that they introduce into proteins. As a generalized technique, non-natural amino acid substitution into proteins is still in its infancy, and many issues need to be addressed, including efficiency of incorporation, overall yield, and toxicity.…”