View source for 4tmz


==Translation initiation factor eIF5B (517-858) from C. thermophilum, bound to GTPgammaS and potassium==
<StructureSection load='4tmz' size='340' side='right'caption='[[4tmz]], [[Resolution|resolution]] 2.28&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4tmz]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Chaetomium_thermophilum Chaetomium thermophilum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4TMZ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4TMZ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.28&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=GSP:5-GUANOSINE-DIPHOSPHATE-MONOTHIOPHOSPHATE'>GSP</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=4tmz FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4tmz OCA], [https://pdbe.org/4tmz PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4tmz RCSB], [https://www.ebi.ac.uk/pdbsum/4tmz PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4tmz ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/IF2P_CHATD IF2P_CHATD] Plays a role in translation initiation. Translational GTPase that catalyzes the joining of the 40S and 60S subunits to form the 80S initiation complex with the initiator methionine-tRNA in the P-site base paired to the start codon. GTP binding and hydrolysis induces conformational changes in the enzyme that renders it active for productive interactions with the ribosome. The release of the enzyme after formation of the initiation complex is a prerequisite to form elongation-competent ribosomes.<ref>PMID:24686316</ref> <ref>PMID:25225612</ref> 
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== Publication Abstract from PubMed ==
Translational GTPases are universally conserved GTP hydrolyzing enzymes, critical for fidelity and speed of ribosomal protein biosynthesis. Despite their central roles, the mechanisms of GTP-dependent conformational switching and GTP hydrolysis that govern the function of trGTPases remain poorly understood. Here, we provide biochemical and high-resolution structural evidence that eIF5B and aEF1A/EF-Tu bound to GTP or GTPgammaS coordinate a monovalent cation (M+) in their active site. Our data reveal that M+ ions form constitutive components of the catalytic machinery in trGTPases acting as structural cofactor to stabilize the GTP-bound "on" state. Additionally, the M+ ion provides a positive charge into the active site analogous to the arginine-finger in the Ras-RasGAP system indicating a similar role as catalytic element that stabilizes the transition state of the hydrolysis reaction. In sequence and structure, the coordination shell for the M+ ion is, with exception of eIF2gamma, highly conserved among trGTPases from bacteria to human. We therefore propose a universal mechanism of M+-dependent conformational switching and GTP hydrolysis among trGTPases with important consequences for the interpretation of available biochemical and structural data.

A monovalent cation acts as structural and catalytic cofactor in translational GTPases.,Kuhle B, Ficner R EMBO J. 2014 Sep 15. pii: e201488517. PMID:25225612<ref>PMID:25225612</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 4tmz" style="background-color:#fffaf0;"></div>

==See Also==
*[[Eukaryotic initiation factor 3D structures|Eukaryotic initiation factor 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Chaetomium thermophilum]]
[[Category: Large Structures]]
[[Category: Ficner R]]
[[Category: Kuhle B]]