View source for 1ox4


==TOWARDS UNDERSTANDING THE MECHANISM OF THE COMPLEX CYCLIZATION REACTION CATALYZED BY IMIDAZOLE GLYCEROPHOSPHATE SYNTHASE==
<StructureSection load='1ox4' size='340' side='right'caption='[[1ox4]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1ox4]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1OX4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1OX4 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]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CYD:2-AMINO-6-(CYSTEIN-S-YL)-5-OXO-HEXANOIC+ACID'>CYD</scene>, <scene name='pdbligand=NI:NICKEL+(II)+ION'>NI</scene>, <scene name='pdbligand=POP:PYROPHOSPHATE+2-'>POP</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=1ox4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ox4 OCA], [https://pdbe.org/1ox4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ox4 RCSB], [https://www.ebi.ac.uk/pdbsum/1ox4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ox4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/HIS5_YEAST HIS5_YEAST] IGPS catalyzes the conversion of PRFAR and glutamine to IGP, AICAR and glutamate. The glutamine amidotransferase domain provides the ammonia necessary to the cyclase domain to produce IGP and AICAR from PRFAR.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ox/1ox4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1ox4 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Imidazole glycerol phosphate synthase catalyzes formation of the imidazole ring in histidine biosynthesis. The enzyme is also a glutamine amidotransferase, which produces ammonia in a glutaminase active site and channels it through a 30-A internal tunnel to a cyclase active site. Glutaminase activity is impaired in the resting enzyme, and stimulated by substrate binding in the cyclase active site. The signaling mechanism was investigated in the crystal structure of a ternary complex in which the glutaminase active site was inactivated by a glutamine analogue and the unstable cyclase substrate was cryo-trapped in the active site. The orientation of N(1)-(5'-phosphoribulosyl)-formimino-5-aminoimidazole-4-carboxamide ribonucleotide in the cyclase active site implicates one side of the cyclase domain in signaling to the glutaminase domain. This side of the cyclase domain contains the interdomain hinge. Two interdomain hydrogen bonds, which do not exist in more open forms of the enzyme, are proposed as molecular signals. One hydrogen bond connects the cyclase domain to the substrate analogue in the glutaminase active site. The second hydrogen bond connects to a peptide that forms an oxyanion hole for stabilization of transient negative charge during glutamine hydrolysis. Peptide rearrangement induced by a fully closed domain interface is proposed to activate the glutaminase by unblocking the oxyanion hole. This interpretation is consistent with biochemical results [Myers, R. S., et al., (2003) Biochemistry 42, 7013-7022, the accompanying paper in this issue] and with structures of the free enzyme and a binary complex with a second glutamine analogue.

Toward understanding the mechanism of the complex cyclization reaction catalyzed by imidazole glycerolphosphate synthase: crystal structures of a ternary complex and the free enzyme.,Chaudhuri BN, Lange SC, Myers RS, Davisson VJ, Smith JL Biochemistry. 2003 Jun 17;42(23):7003-12. PMID:12795595<ref>PMID:12795595</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 1ox4" style="background-color:#fffaf0;"></div>

==See Also==
*[[IGPS 3D structures|IGPS 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Saccharomyces cerevisiae]]
[[Category: Chaudhuri BN]]
[[Category: Smith JL]]