View source for 4rl4


==Crystal structure of GTP cyclohydrolase II from Helicobacter pylori 26695==
<StructureSection load='4rl4' size='340' side='right'caption='[[4rl4]], [[Resolution|resolution]] 2.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4rl4]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Helicobacter_pylori_26695 Helicobacter pylori 26695]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4RL4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4RL4 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]] 2.199&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PPV:PYROPHOSPHATE'>PPV</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=4rl4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4rl4 OCA], [https://pdbe.org/4rl4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4rl4 RCSB], [https://www.ebi.ac.uk/pdbsum/4rl4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4rl4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RIBA_HELPY RIBA_HELPY] Catalyzes the conversion of GTP to 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate (DARP), formate and pyrophosphate.<ref>PMID:9574900</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
GTP cyclohydrolase II (GCHII), catalyzes the conversion of GTP to 2,5-diamino-6-beta-ribosyl-4(3H)-pyrimidinone-5'-phosphate and has been shown to be essential for pathogens. Here we describe the biochemical, kinetic and structural characterization of GCHII from Helicobacter pylori (hGCHII). The crystal structure of hGCHII, unlike other GCHII structures, revealed that cysteines at the active site existed in oxidized state forming two disulfide bonds and lacked Zn2+ that was shown to be indispensable for catalytic activity in other species. However, incubation of hGCHII with hydrogen peroxide, an oxidizing agent, followed by PAR-assay showed that Zn2+ was intrinsically present, indicating that all cysteines at the catalytic site remained in reduced state. Moreover, site directed mutagenesis of catalytic site cysteines revealed that only three, out of four cysteines were essential for hGCHII activity. These results, though, indicated that hGCHII crystallized in oxidized form, the expulsion of Zn2+ upon oxidation of catalytic cysteines revealed its ability to act in response to the redox environment. Exploring further, incubation of hGCHII with reversible thiol modifying agent S-methyl-methane-thiosulfonate resulted in loss of GCHII activity due to oxidation of its cysteine residues as revealed by mass spectrometry studies. However, addition of reducing agent DTT partially restored the hGCHII catalytic activity. Taken together, these results demonstrate that hGCHII can regulate its catalytic activity depending on the redox environment, a function hitherto unknown for GCHII.

Structural and biochemical characterization of GTP cyclohydrolase II from Helicobacter pylori reveals its redox dependent catalytic activity.,Yadav S, Karthikeyan S J Struct Biol. 2015 Aug 10. pii: S1047-8477(15)30042-3. doi:, 10.1016/j.jsb.2015.08.004. PMID:26272484<ref>PMID:26272484</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4rl4" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cyclohydrolase 3D structures|Cyclohydrolase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Helicobacter pylori 26695]]
[[Category: Large Structures]]
[[Category: Karthikeyan S]]
[[Category: Yadav S]]