3IYR

tmRNA-SmpB: a journey to the center of the bacterial ribosome

Summary for 3IYR

• Entry DOI: 10.2210/pdb3iyr/pdb
• Related: 3IYQ
• EMDB information: 5189
• Descriptor: tmRNA, SsrA-binding protein (2 entities in total)
• Functional Keywords: tmrna, smpb, ribosome, trans-translation, ribosomal protein-rna complex, ribosomal protein/rna
• Biological source: Thermus thermophilus; More
• Total number of polymer chains: 2
• Total formula weight: 130302.12

Authors

Weis, F.,Bron, P.,Giudice, E.,Rolland, J.P.,Thomas, D.,Felden, B.,Gillet, R. (deposition date: 2010-04-16, release date: 2010-10-20, Last modification date: 2024-02-21)

Primary citation

Weis, F.,Bron, P.,Giudice, E.,Rolland, J.P.,Thomas, D.,Felden, B.,Gillet, R.
tmRNA-SmpB: a journey to the centre of the bacterial ribosome.
Embo J., 29:3810-3818, 2010

PubMed Abstract: Ribosomes mediate protein synthesis by decoding the information carried by messenger RNAs (mRNAs) and catalysing peptide bond formation between amino acids. When bacterial ribosomes stall on incomplete messages, the trans-translation quality control mechanism is activated by the transfer-messenger RNA bound to small protein B (tmRNA-SmpB ribonucleoprotein complex). Trans-translation liberates the stalled ribosomes and triggers degradation of the incomplete proteins. Here, we present the cryo-electron microscopy structures of tmRNA-SmpB accommodated or translocated into stalled ribosomes. Two atomic models for each state are proposed. This study reveals how tmRNA-SmpB crosses the ribosome and how, as the problematic mRNA is ejected, the tmRNA resume codon is placed onto the ribosomal decoding site by new contacts between SmpB and the nucleotides upstream of the tag-encoding sequence. This provides a structural basis for the transit of the large tmRNA-SmpB complex through the ribosome and for the means by which the tmRNA internal frame is set for translation to resume.

PubMed: 20953161
DOI: 10.1038/emboj.2010.252

Experimental method

ELECTRON MICROSCOPY (13 Å)