Miscoding-induced stalling of substrate translocation on the bacterial ribosome

Proc Natl Acad Sci U S A. 2017 Oct 10;114(41):E8603-E8610. doi: 10.1073/pnas.1707539114. Epub 2017 Sep 25.


Directional transit of the ribosome along the messenger RNA (mRNA) template is a key determinant of the rate and processivity of protein synthesis. Imaging of the multistep translocation mechanism using single-molecule FRET has led to the hypothesis that substrate movements relative to the ribosome resolve through relatively long-lived late intermediates wherein peptidyl-tRNA enters the P site of the small ribosomal subunit via reversible, swivel-like motions of the small subunit head domain within the elongation factor G (GDP)-bound ribosome complex. Consistent with translocation being rate-limited by recognition and productive engagement of peptidyl-tRNA within the P site, we now show that base-pairing mismatches between the peptidyl-tRNA anticodon and the mRNA codon dramatically delay this rate-limiting, intramolecular process. This unexpected relationship between aminoacyl-tRNA decoding and translocation suggests that miscoding antibiotics may impact protein synthesis by impairing the recognition of peptidyl-tRNA in the small subunit P site during EF-G-catalyzed translocation. Strikingly, we show that elongation factor P (EF-P), traditionally known to alleviate ribosome stalling at polyproline motifs, can efficiently rescue translocation defects arising from miscoding. These findings help reveal the nature and origin of the rate-limiting steps in substrate translocation on the bacterial ribosome and indicate that EF-P can aid in resuming translation elongation stalled by miscoding errors.

Keywords: EF-P; aminoglycosides; fidelity; ribosome; translocation.

Publication types

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

MeSH terms

  • Anticodon
  • Bacteria / metabolism*
  • Codon
  • Guanosine Triphosphate / metabolism
  • Peptide Elongation Factor G / chemistry
  • Peptide Elongation Factor G / metabolism*
  • Peptide Elongation Factors / chemistry
  • Peptide Elongation Factors / metabolism*
  • Protein Biosynthesis*
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism*
  • RNA, Transfer, Amino Acyl / chemistry
  • RNA, Transfer, Amino Acyl / metabolism*
  • Ribosomes / chemistry
  • Ribosomes / metabolism*


  • Anticodon
  • Codon
  • Peptide Elongation Factor G
  • Peptide Elongation Factors
  • RNA, Messenger
  • RNA, Transfer, Amino Acyl
  • factor EF-P
  • tRNA, peptidyl-
  • Guanosine Triphosphate