Ribosome rearrangements at the onset of translational bypassing

Sci Adv. 2017 Jun 7;3(6):e1700147. doi: 10.1126/sciadv.1700147. eCollection 2017 Jun.

Abstract

Bypassing is a recoding event that leads to the translation of two distal open reading frames into a single polypeptide chain. We present the structure of a translating ribosome stalled at the bypassing take-off site of gene 60 of bacteriophage T4. The nascent peptide in the exit tunnel anchors the P-site peptidyl-tRNAGly to the ribosome and locks an inactive conformation of the peptidyl transferase center (PTC). The mRNA forms a short dynamic hairpin in the decoding site. The ribosomal subunits adopt a rolling conformation in which the rotation of the small subunit around its long axis causes the opening of the A-site region. Together, PTC conformation and mRNA structure safeguard against premature termination and read-through of the stop codon and reconfigure the ribosome to a state poised for take-off and sliding along the noncoding mRNA gap.

Keywords: bypassing; recoding; ribosome; structure; translation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Models, Molecular
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein Biosynthesis*
  • Protein Conformation
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Ribosome Subunits, Small, Bacterial / metabolism
  • Ribosomes / chemistry
  • Ribosomes / metabolism*
  • Structure-Activity Relationship

Substances

  • Peptides
  • RNA, Messenger