Initiation of Protein Synthesis with Non-Canonical Amino Acids In Vivo

Angew Chem Int Ed Engl. 2020 Feb 17;59(8):3122-3126. doi: 10.1002/anie.201914671. Epub 2020 Jan 21.

Abstract

By transplanting identity elements into E. coli tRNAfMet , we have engineered an orthogonal initiator tRNA (itRNATy2 ) that is a substrate for Methanocaldococcus jannaschii TyrRS. We demonstrate that itRNATy2 can initiate translation in vivo with aromatic non-canonical amino acids (ncAAs) bearing diverse sidechains. Although the initial system suffered from low yields, deleting redundant copies of tRNAfMet from the genome afforded an E. coli strain in which the efficiency of non-canonical initiation equals elongation. With this improved system we produced a protein containing two distinct ncAAs at the first and second positions, an initial step towards producing completely unnatural polypeptides in vivo. This work provides a valuable tool to synthetic biology and demonstrates remarkable versatility of the E. coli translational machinery for initiation with ncAAs in vivo.

Keywords: chemical biology; genetic code expansion; non-canonical amino acids; synthetic biology; translation initiation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acids / metabolism*
  • Humans
  • Protein Biosynthesis / physiology*
  • Protein Engineering / methods*

Substances

  • Amino Acids