View source for 4hsh


==tRNA-guanine transglycosylase Y106F, V233G mutant in complex with queuine==
<StructureSection load='4hsh' size='340' side='right'caption='[[4hsh]], [[Resolution|resolution]] 1.56&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4hsh]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Zymomonas_mobilis_subsp._mobilis_ZM4_=_ATCC_31821 Zymomonas mobilis subsp. mobilis ZM4 = ATCC 31821]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4HSH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4HSH 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]] 1.56&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=QEI:2-AMINO-5-({[(1S,4S,5R)-4,5-DIHYDROXYCYCLOPENT-2-EN-1-YL]AMINO}METHYL)-3,7-DIHYDRO-4H-PYRROLO[2,3-D]PYRIMIDIN-4-ONE'>QEI</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=4hsh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4hsh OCA], [https://pdbe.org/4hsh PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4hsh RCSB], [https://www.ebi.ac.uk/pdbsum/4hsh PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4hsh ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TGT_ZYMMO TGT_ZYMMO] Exchanges the guanine residue with 7-aminomethyl-7-deazaguanine in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr). After this exchange, a cyclopentendiol moiety is attached to the 7-aminomethyl group of 7-deazaguanine, resulting in the hypermodified nucleoside queuosine (Q) (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine).[HAMAP-Rule:MF_00168]
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Bacterial tRNA-guanine transglycosylase (Tgt) catalyses the exchange of the genetically encoded guanine at the wobble position of tRNAs(His,Tyr,Asp,Asn) by the premodified base preQ1, which is further converted to queuine at the tRNA level. As eucaryotes are not able to synthesise queuine de novo but acquire it through their diet, eucaryotic Tgt directly inserts the hypermodified base into the wobble position of the tRNAs mentioned above. Bacterial Tgt is required for the efficient pathogenicity of Shigella sp, the causative agent of bacillary dysentery and, hence, it constitutes a putative target for the rational design of anti-Shigellosis compounds. Since mammalian Tgt is known to be indirectly essential to the conversion of phenylalanine to tyrosine, it is necessary to create substances which only inhibit bacterial but not eucaryotic Tgt. Therefore, it seems of utmost importance to study selectivity-determining features within both types of proteins. Homology models of Caenorhabditis elegans Tgt and human Tgt suggest that the replacement of Cys158 and Val233 in bacterial Tgt (Zymomonas mobilis Tgt numbering) by valine and accordingly glycine in eucaryotic Tgt largely accounts for the different substrate specificities. In the present study we have created mutated variants of Z. mobilis Tgt in order to investigate the impact of a Cys158Val and a Val233Gly exchange on catalytic activity and substrate specificity. Using enzyme kinetics and X-ray crystallography, we gained evidence that the Cys158Val mutation reduces the affinity to preQ1 while leaving the affinity to guanine unaffected. The Val233Gly exchange leads to an enlarged substrate binding pocket, that is necessary to accommodate queuine in a conformation compatible with the intermediately covalently bound tRNA molecule. Contrary to our expectations, we found that a priori queuine is recognised by the binding pocket of bacterial Tgt without, however, being used as a substrate.

Investigation of specificity determinants in bacterial tRNA-guanine transglycosylase reveals queuine, the substrate of its eucaryotic counterpart, as inhibitor.,Biela I, Tidten-Luksch N, Immekus F, Glinca S, Nguyen TX, Gerber HD, Heine A, Klebe G, Reuter K PLoS One. 2013 May 21;8(5):e64240. doi: 10.1371/journal.pone.0064240. Print 2013. PMID:23704982<ref>PMID:23704982</ref>

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

==See Also==
*[[TRNA-guanine transglycosylase 3D structures|TRNA-guanine transglycosylase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Zymomonas mobilis subsp. mobilis ZM4 = ATCC 31821]]
[[Category: Biela I]]
[[Category: Heine A]]
[[Category: Klebe G]]
[[Category: Reuter K]]
[[Category: Tidten-Luksch N]]