A kinetic safety gate controlling the delivery of unnatural amino acids to the ribosome

J Am Chem Soc. 2013 Nov 13;135(45):17031-8. doi: 10.1021/ja407511q. Epub 2013 Oct 29.


Improving the yield of unnatural amino acid incorporation is an important challenge in producing novel designer proteins with unique chemical properties. Here we examine the mechanisms that restrict the incorporation of the fluorescent unnatural amino acid εNH2-Bodipy576/589-lysine (BOP-Lys) into a model protein. While the delivery of BOP-Lys-tRNA(Lys) to the ribosome is limited by its poor binding to elongation factor Tu (EF-Tu), the yield of incorporation into peptide is additionally controlled at the step of BOP-Lys-tRNA release from EF-Tu into the ribosome. The unnatural amino acid appears to disrupt the interactions that balance the strength of tRNA binding to EF-Tu-GTP with the velocity of tRNA dissociation from EF-Tu-GDP on the ribosome, which ensure uniform incorporation of standard amino acids. Circumventing this potential quality control checkpoint that specifically prevents incorporation of unnatural amino acids into proteins may provide a new strategy to increase yields of unnatural polymers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Boron Compounds / chemistry
  • Escherichia coli / chemistry
  • Escherichia coli / metabolism*
  • Fluorescent Dyes / chemistry
  • Guanosine Triphosphate / metabolism
  • Kinetics
  • Lysine / analogs & derivatives*
  • Models, Molecular
  • Peptide Elongation Factor Tu / chemistry
  • Peptide Elongation Factor Tu / metabolism*
  • RNA, Transfer / metabolism
  • Ribosomes / metabolism*
  • Thermus thermophilus / chemistry
  • Thermus thermophilus / metabolism*


  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Bacterial Proteins
  • Boron Compounds
  • Fluorescent Dyes
  • Guanosine Triphosphate
  • RNA, Transfer
  • Peptide Elongation Factor Tu
  • Lysine