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New page: left|200px<br /><applet load="1fp4" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fp4, resolution 2.5Å" /> '''CRYSTAL STRUCTURE OF ...
 
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[[Image:1fp4.jpg|left|200px]]<br /><applet load="1fp4" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1fp4, resolution 2.5&Aring;" />
'''CRYSTAL STRUCTURE OF THE ALPHA-H195Q MUTANT OF NITROGENASE'''<br />


==Overview==
==CRYSTAL STRUCTURE OF THE ALPHA-H195Q MUTANT OF NITROGENASE==
EPR signals observed under CO and C(2)H(2) during nitrogenase turnover, were investigated for the alpha-Gln(195) MoFe protein, an altered form for, which the alpha-His(195) residue has been substituted by glutamine. Under, CO, samples show S = 1/2 hi- and lo-CO EPR signals identical to those, recognized for the wild-type protein, whereas the S = 3/2 signals, generated under high CO/high flux conditions differ. Previous work has, revealed that the EPR spectrum generated under C(2)H(2) exhibits a signal, (S(EPR1)) originating from the FeMo-cofactor having two or more bound, C(2)H(2) adducts and a second signal (S(EPR2)) arising from a radical, species [Sorlie, M., Christiansen, J., Dean, D. R., and Hales, B. J., (1999) J. Am. Chem. Soc. 121, 9457-9458]. Pressure-dependent studies show, that the intensity of these signals has a sigmoidal dependency at low, pressures and maximized at 0.1 atm C(2)H(2) with a subsequent decrease in, steady-state intensity at higher pressures. Analogous signals are not, recognized for the wild-type MoFe protein. Analysis of the principal, g-factors of S(EPR2) suggests that it either represents an unusual metal, cluster or is a carboxylate centered radical possibly originating from, homocitrate. Both S(EPR1) and S(EPR2) exhibit similar relaxation, properties that are atypical for S = 1/2 signals originating from Fe-S, clusters or radicals and indicate a coupled relaxation pathway. The, alpha-Gln(195) MoFe protein also exhibits these signals when incubated, under turnover conditions in the presence of C(2)H(4). Under these, conditions, additional inflections in the g 4-6 region assigned to, ground-state transitions of an S = 3/2 spin system are also recognized and, assigned to turnover states of the MoFe protein without C(2)H(4) bound., The structure of alpha-Gln(195) was crystallographically determined and, found to be virtually identical to that of the wild-type MoFe protein, except for replacement of an NuH-S hydrogen bond interaction between, FeMo-cofactor and the imidazole side chain of alpha-His(195) by an, analogous interaction involving Gln.
<StructureSection load='1fp4' size='340' side='right'caption='[[1fp4]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1fp4]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FP4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1FP4 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=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CFM:FE-MO-S+CLUSTER'>CFM</scene>, <scene name='pdbligand=CLP:FE-S+CLUSTER'>CLP</scene>, <scene name='pdbligand=HCA:3-HYDROXY-3-CARBOXY-ADIPIC+ACID'>HCA</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=1fp4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1fp4 OCA], [https://pdbe.org/1fp4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1fp4 RCSB], [https://www.ebi.ac.uk/pdbsum/1fp4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1fp4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NIFD_AZOVI NIFD_AZOVI] This molybdenum-iron protein is part of the nitrogenase complex that catalyzes the key enzymatic reactions in nitrogen fixation.
== 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/fp/1fp4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1fp4 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
EPR signals observed under CO and C(2)H(2) during nitrogenase turnover were investigated for the alpha-Gln(195) MoFe protein, an altered form for which the alpha-His(195) residue has been substituted by glutamine. Under CO, samples show S = 1/2 hi- and lo-CO EPR signals identical to those recognized for the wild-type protein, whereas the S = 3/2 signals generated under high CO/high flux conditions differ. Previous work has revealed that the EPR spectrum generated under C(2)H(2) exhibits a signal (S(EPR1)) originating from the FeMo-cofactor having two or more bound C(2)H(2) adducts and a second signal (S(EPR2)) arising from a radical species [Sorlie, M., Christiansen, J., Dean, D. R., and Hales, B. J. (1999) J. Am. Chem. Soc. 121, 9457-9458]. Pressure-dependent studies show that the intensity of these signals has a sigmoidal dependency at low pressures and maximized at 0.1 atm C(2)H(2) with a subsequent decrease in steady-state intensity at higher pressures. Analogous signals are not recognized for the wild-type MoFe protein. Analysis of the principal g-factors of S(EPR2) suggests that it either represents an unusual metal cluster or is a carboxylate centered radical possibly originating from homocitrate. Both S(EPR1) and S(EPR2) exhibit similar relaxation properties that are atypical for S = 1/2 signals originating from Fe-S clusters or radicals and indicate a coupled relaxation pathway. The alpha-Gln(195) MoFe protein also exhibits these signals when incubated under turnover conditions in the presence of C(2)H(4). Under these conditions, additional inflections in the g 4-6 region assigned to ground-state transitions of an S = 3/2 spin system are also recognized and assigned to turnover states of the MoFe protein without C(2)H(4) bound. The structure of alpha-Gln(195) was crystallographically determined and found to be virtually identical to that of the wild-type MoFe protein except for replacement of an NuH-S hydrogen bond interaction between FeMo-cofactor and the imidazole side chain of alpha-His(195) by an analogous interaction involving Gln.


==About this Structure==
Mechanistic features and structure of the nitrogenase alpha-Gln195 MoFe protein.,Sorlie M, Christiansen J, Lemon BJ, Peters JW, Dean DR, Hales BJ Biochemistry. 2001 Feb 13;40(6):1540-9. PMID:11327812<ref>PMID:11327812</ref>
1FP4 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii] with CA, HCA, CFM and CLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Nitrogenase Nitrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.18.6.1 1.18.6.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1FP4 OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
Mechanistic features and structure of the nitrogenase alpha-Gln195 MoFe protein., Sorlie M, Christiansen J, Lemon BJ, Peters JW, Dean DR, Hales BJ, Biochemistry. 2001 Feb 13;40(6):1540-9. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11327812 11327812]
</div>
<div class="pdbe-citations 1fp4" style="background-color:#fffaf0;"></div>
 
==See Also==
*[[Nitrogenase 3D structures|Nitrogenase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Azotobacter vinelandii]]
[[Category: Azotobacter vinelandii]]
[[Category: Nitrogenase]]
[[Category: Large Structures]]
[[Category: Protein complex]]
[[Category: Christiansen J]]
[[Category: Christiansen, J.]]
[[Category: Dean DR]]
[[Category: Dean, D.R.]]
[[Category: Hales BJ]]
[[Category: Hales, B.J.]]
[[Category: Lemon BJ]]
[[Category: Lemon, B.J.]]
[[Category: Peters JW]]
[[Category: Peters, J.W.]]
[[Category: Sorlie M]]
[[Category: Sorlie, M.]]
[[Category: CA]]
[[Category: CFM]]
[[Category: CLP]]
[[Category: HCA]]
[[Category: iron-sulfur-molybdenum protein]]
 
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