View source for 1gn4


==H145E mutant of Mycobacterium tuberculosis iron-superoxide dismutase.==
<StructureSection load='1gn4' size='340' side='right'caption='[[1gn4]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1gn4]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GN4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1GN4 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=MN:MANGANESE+(II)+ION'>MN</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=1gn4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1gn4 OCA], [https://pdbe.org/1gn4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1gn4 RCSB], [https://www.ebi.ac.uk/pdbsum/1gn4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1gn4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SODF_MYCTU SODF_MYCTU] Destroys superoxide anion radicals which are normally produced within the cells and which are toxic to biological systems.
== 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/gn/1gn4_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=1gn4 ConSurf].
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== Publication Abstract from PubMed ==
We have refined the X-ray structures of two site-directed mutants of the iron-dependent superoxide dismutase (SOD) from Mycobacterium tuberculosis. These mutations which affect residue 145 in the enzyme (H145Q and H145E) were designed to alter its metal-ion specificity. This residue is either Gln or His in homologous SOD enzymes and has previously been shown to play a role in active-site interactions since its side-chain helps to coordinate the metal ion via a solvent molecule which is thought to be a hydroxide ion. The mutations were based on the observation that in the closely homologous manganese dependent SOD from Mycobacterium leprae, the only significant difference from the M. tuberculosis SOD within 10 A of the metal-binding site is the substitution of Gln for His at position 145. Hence an H145Q mutant of the M. tuberculosis (TB) SOD was engineered to investigate this residue's role in metal ion dependence and an isosteric H145E mutant was also expressed. The X-ray structures of the H145Q and H145E mutants have been solved at resolutions of 4.0 A and 2.5 A, respectively, confirming that neither mutation has any gross effects on the conformation of the enzyme or the structure of the active site. The residue substitutions are accommodated in the enzyme's three-dimensional structure by small local conformational changes. Peroxide inhibition experiments and atomic absorption spectroscopy establish surprisingly the H145E mutant SOD has manganese bound to it whereas the H145Q mutant SOD retains iron as the active-site metal. This alteration in metal specificity may reflect on the preference of manganese ions for anionic ligands.

Engineering a change in metal-ion specificity of the iron-dependent superoxide dismutase from Mycobacterium tuberculosis-- X-ray structure analysis of site-directed mutants.,Bunting K, Cooper JB, Badasso MO, Tickle IJ, Newton M, Wood SP, Zhang Y, Young D Eur J Biochem. 1998 Feb 1;251(3):795-803. PMID:9490054<ref>PMID:9490054</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 1gn4" style="background-color:#fffaf0;"></div>

==See Also==
*[[Superoxide dismutase 3D structures|Superoxide dismutase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mycobacterium tuberculosis]]
[[Category: Badasso MO]]
[[Category: Bunting KA]]
[[Category: Cooper JB]]
[[Category: Newton M]]
[[Category: Tickle IJ]]
[[Category: Wood SP]]
[[Category: Young DB]]
[[Category: Zhang Y]]