Recycling of aborted ribosomal 50S subunit-nascent chain-tRNA complexes by the heat shock protein Hsp15

Linhua Jiang, Christiane Schaffitzel, Rouven Bingel-Erlenmeyer, Nenad Ban, Philipp Korber, Roman I Koning, Daniël C de Geus, Jasper R Plaisier, Jan Pieter Abrahams

Research output: Contribution to journalArticle (Academic Journal)peer-review

34 Citations (Scopus)


When heat shock prematurely dissociates a translating bacterial ribosome, its 50S subunit is prevented from reinitiating protein synthesis by tRNA covalently linked to the unfinished protein chain that remains threaded through the exit tunnel. Hsp15, a highly upregulated bacterial heat shock protein, reactivates such dead-end complexes. Here, we show with cryo-electron microscopy reconstructions and functional assays that Hsp15 translocates the tRNA moiety from the A site to the P site of stalled 50S subunits. By stabilizing the tRNA in the P site, Hsp15 indirectly frees up the A site, allowing a release factor to land there and cleave off the tRNA. Such a release factor must be stop codon independent, suggesting a possible role for a poorly characterized class of putative release factors that are upregulated by cellular stress, lack a codon recognition domain and are conserved in eukaryotes.

Original languageEnglish
Pages (from-to)1357-67
Number of pages11
JournalJournal of Molecular Biology
Issue number5
Publication statusPublished - 13 Mar 2009


  • Cryoelectron Microscopy
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Heat-Shock Proteins
  • Models, Molecular
  • Puromycin
  • RNA, Bacterial
  • RNA, Transfer
  • Ribosome Subunits, Large, Bacterial


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