Summary information and primary citation

PDB-id
3bbx; DSSR-derived features in text and JSON formats
Class
ribosome
Method
cryo-EM (10.0 Å)
Summary
The hsp15 protein fitted into the low resolution cryo-EM map of the 50s.nc-trna.hsp15 complex
Reference
Jiang L, Schaffitzel C, Bingel-Erlenmeyer R, Ban N, Korber P, Koning RI, de Geus DC, Plaisier JR, Abrahams JP (2009): "Recycling of Aborted Ribosomal 50S Subunit-Nascent Chain-tRNA Complexes by the Heat Shock Protein Hsp15." J.Mol.Biol., 386, 1357-1367. doi: 10.1016/j.jmb.2008.10.079.
Abstract
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.

Cartoon-block schematics in six views (download the tarball)

PyMOL session file Download PDB file View in 3Dmol.js