View source for 7oj0


==Cryo-EM structure of 70S ribosome stalled with TnaC peptide and RF2==
<StructureSection load='7oj0' size='340' side='right'caption='[[7oj0]], [[Resolution|resolution]] 3.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7oj0]] is a 10 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7OJ0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7OJ0 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=1MG:1N-METHYLGUANOSINE-5-MONOPHOSPHATE'>1MG</scene>, <scene name='pdbligand=2MA:2-METHYLADENOSINE-5-MONOPHOSPHATE'>2MA</scene>, <scene name='pdbligand=2MG:2N-METHYLGUANOSINE-5-MONOPHOSPHATE'>2MG</scene>, <scene name='pdbligand=3TD:(1S)-1,4-ANHYDRO-1-(3-METHYL-2,4-DIOXO-1,2,3,4-TETRAHYDROPYRIMIDIN-5-YL)-5-O-PHOSPHONO-D-RIBITOL'>3TD</scene>, <scene name='pdbligand=4OC:4N,O2-METHYLCYTIDINE-5-MONOPHOSPHATE'>4OC</scene>, <scene name='pdbligand=5MC:5-METHYLCYTIDINE-5-MONOPHOSPHATE'>5MC</scene>, <scene name='pdbligand=5MU:5-METHYLURIDINE+5-MONOPHOSPHATE'>5MU</scene>, <scene name='pdbligand=6MZ:N6-METHYLADENOSINE-5-MONOPHOSPHATE'>6MZ</scene>, <scene name='pdbligand=G7M:N7-METHYL-GUANOSINE-5-MONOPHOSPHATE'>G7M</scene>, <scene name='pdbligand=MA6:6N-DIMETHYLADENOSINE-5-MONOPHOSHATE'>MA6</scene>, <scene name='pdbligand=MEQ:N5-METHYLGLUTAMINE'>MEQ</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=OMC:O2-METHYLYCYTIDINE-5-MONOPHOSPHATE'>OMC</scene>, <scene name='pdbligand=OMG:O2-METHYLGUANOSINE-5-MONOPHOSPHATE'>OMG</scene>, <scene name='pdbligand=OMU:O2-METHYLURIDINE+5-MONOPHOSPHATE'>OMU</scene>, <scene name='pdbligand=PSU:PSEUDOURIDINE-5-MONOPHOSPHATE'>PSU</scene>, <scene name='pdbligand=TRP:TRYPTOPHAN'>TRP</scene>, <scene name='pdbligand=UR3:3-METHYLURIDINE-5-MONOPHOSHATE'>UR3</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=7oj0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7oj0 OCA], [https://pdbe.org/7oj0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7oj0 RCSB], [https://www.ebi.ac.uk/pdbsum/7oj0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7oj0 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== 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<ref>PMID:34403461</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 7oj0" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ribosome 3D structures|Ribosome 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Becker T]]
[[Category: Beckmann R]]
[[Category: Berninghausen O]]
[[Category: Cheng J]]
[[Category: Heijne G]]
[[Category: Kudva R]]
[[Category: Su T]]