Mechanism of ribosome rescue by ArfA and RF2

Gabriel Demo, Egor Svidritskiy, Rohini Madireddy, Ruben Diaz-Avalos, Timothy Grant, Nikolaus Grigorieff, Duncan Sousa, Andrei A. Korostelev

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


ArfA rescues ribosomes stalled on truncated mRNAs by recruiting release factor RF2, which normally binds stop codons to catalyze peptide release. We report two 3.2 A resolution cryo-EM structures – determined from a single sample – of the 70S ribosome with ArfA.RF2 in the A site. In both states, the ArfA C-terminus occupies the mRNA tunnel downstream of the A site. One state contains a compact inactive RF2 conformation. Ordering of the ArfA N-terminus in the second state rearranges RF2 into an extended conformation that docks the catalytic GGQ motif into the peptidyl-transferase center. Our work thus reveals the structural dynamics of ribosome rescue. The structures demonstrate how ArfA ‘senses’ the vacant mRNA tunnel and activates RF2 to mediate peptide release without a stop codon, allowing stalled ribosomes to be recycled.

Original languageEnglish (US)
Article numbere23687
StatePublished - Mar 16 2017
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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