View source for 2ntk


==Crystal structure of PurO/IMP from Methanothermobacter thermoautotrophicus==
<StructureSection load='2ntk' size='340' side='right'caption='[[2ntk]], [[Resolution|resolution]] 2.03&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2ntk]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Methanothermobacter_thermautotrophicus Methanothermobacter thermautotrophicus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2NTK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2NTK 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]] 2.03&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=IMP:INOSINIC+ACID'>IMP</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=2ntk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ntk OCA], [https://pdbe.org/2ntk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ntk RCSB], [https://www.ebi.ac.uk/pdbsum/2ntk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ntk ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PURO_METTH PURO_METTH] Catalyzes the cyclization of 5-formylamidoimidazole-4-carboxamide ribonucleotide to IMP (By similarity).
== 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/nt/2ntk_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=2ntk ConSurf].
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== Publication Abstract from PubMed ==
Inosine 5'-monophosphate (IMP) cyclohydrolase catalyzes the cyclization of 5-formaminoimidazole-4-carboxamide ribonucleotide (FAICAR) to IMP in the final step of de novo purine biosynthesis. Two major types of this enzyme have been discovered to date: PurH in Bacteria and Eukarya and PurO in Archaea. The structure of the MTH1020 gene product from Methanothermobacter thermoautotrophicus was previously solved without functional annotation but shows high amino acid sequence similarity to other PurOs. We determined the crystal structure of the MTH1020 gene product in complex with either IMP or 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) at 2.0 and 2.6 A resolution, respectively. On the basis of the sequence analysis, ligand-bound structures, and biochemical data, MTH1020 is confirmed as an archaeal IMP cyclohydrolase, thus designated as MthPurO. MthPurO has a four-layered alphabeta betaalpha core structure, showing an N-terminal nucleophile (NTN) hydrolase fold. The active site is located at the deep pocket between two central beta-sheets and contains residues strictly conserved within PurOs. Comparisons of the two types of IMP cyclohydrolase, PurO and PurH, revealed that there are no similarities in sequence, structure, or the active site architecture, suggesting that they are evolutionarily not related to each other. The MjR31K mutant of PurO from Methanocaldococcus jannaschii showed 76% decreased activity and the MjE102Q mutation completely abolished enzymatic activity, suggesting that these highly conserved residues play critical roles in catalysis. Interestingly, green fluorescent protein (GFP), which has no structural homology to either PurO or PurH but catalyzes a similar intramolecular cyclohydrolase reaction required for chromophore maturation, utilizes Arg96 and Glu222 in a mechanism analogous to that of PurO.

A novel function for the N-terminal nucleophile hydrolase fold demonstrated by the structure of an archaeal inosine monophosphate cyclohydrolase.,Kang YN, Tran A, White RH, Ealick SE Biochemistry. 2007 May 1;46(17):5050-62. Epub 2007 Apr 4. PMID:17407260<ref>PMID:17407260</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 2ntk" style="background-color:#fffaf0;"></div>

==See Also==
*[[Bifunctional purine biosynthesis protein PURH|Bifunctional purine biosynthesis protein PURH]]
*[[Cyclohydrolase 3D structures|Cyclohydrolase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Methanothermobacter thermautotrophicus]]
[[Category: Ealick SE]]
[[Category: Kang YN]]
[[Category: Tran A]]
[[Category: White RH]]