View source for 7oiz


==Cryo-EM structure of 70S ribosome stalled with TnaC peptide==
<StructureSection load='7oiz' size='340' side='right'caption='[[7oiz]], [[Resolution|resolution]] 2.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[7oiz]] 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=7OIZ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7OIZ 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]] 2.9&#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=PAR:PAROMOMYCIN'>PAR</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=7oiz FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7oiz OCA], [https://pdbe.org/7oiz PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7oiz RCSB], [https://www.ebi.ac.uk/pdbsum/7oiz PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7oiz ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RS8_ECOLI RS8_ECOLI] One of the primary rRNA binding proteins, it binds directly to 16S rRNA central domain where it helps coordinate assembly of the platform of the 30S subunit (By similarity).[HAMAP-Rule:MF_01302_B]  Protein S8 is a translational repressor protein, it controls the translation of the spc operon by binding to its mRNA.[HAMAP-Rule:MF_01302_B]
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== 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 7oiz" 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]]