7p3k

Cryo-EM structure of 70S ribosome stalled with TnaC peptide (control)

spinqualitylabelsall models 7p3k, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7p3k is a 10 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.9Å Ligands: 1MG, 2MA, 2MG, 3TD, 4OC, 5MC, 5MU, 6MZ, CLM, G7M, MA6, MEQ, MG, OMC, OMG, OMU, PSU, UR3, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RS2_ECOLI Publication Abstract from PubMed In Escherichia coli, elevated levels of free l-tryptophan (l-Trp) promote translational arrest of the TnaC peptide by inhibiting its termination. However, the mechanism by which translation-termination by the UGA-specific decoding release factor 2 (RF2) is inhibited at the UGA stop codon of stalled TnaC-ribosome-nascent chain complexes has so far been ambiguous. This study presents cryo-EM structures for ribosomes stalled by TnaC in the absence and presence of RF2 at average resolutions of 2.9 and 3.5 A, respectively. Stalled TnaC assumes a distinct conformation composed of two small alpha-helices that act together with residues in the peptide exit tunnel (PET) to coordinate a single L-Trp molecule. In addition, while the peptidyl-transferase center (PTC) is locked in a conformation that allows RF2 to adopt its canonical position in the ribosome, it prevents the conserved and catalytically essential GGQ motif of RF2 from adopting its active conformation in the PTC. This explains how translation of the TnaC peptide effectively allows the ribosome to function as a L-Trp-specific small-molecule sensor that regulates the tnaCAB operon. Structural basis of l-tryptophan-dependent inhibition of release factor 2 by the TnaC arrest peptide.,Su T, Kudva R, Becker T, Buschauer R, Komar T, Berninghausen O, von Heijne G, Cheng J, Beckmann R Nucleic Acids Res. 2021 Sep 20;49(16):9539-9547. doi: 10.1093/nar/gkab665. PMID:34403461 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribosome 3D structures

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