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New page: left|200px<br /> <applet load="2gnw" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gnw, resolution 2.400Å" /> '''Crystal structure ...
 
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[[Image:2gnw.gif|left|200px]]<br />
<applet load="2gnw" size="450" color="white" frame="true" align="right" spinBox="true"
caption="2gnw, resolution 2.400&Aring;" />
'''Crystal structure of non-symbiotic plant hemoglobin from rice, B10 mutant F40W'''<br />


==Overview==
==Crystal structure of non-symbiotic plant hemoglobin from rice, B10 mutant F40W==
All plants contain an unusual class of hemoglobins that display, bis-histidyl coordination yet are able to bind exogenous ligands such as, oxygen. Structurally homologous hexacoordinate hemoglobins (hxHbs) are, also found in animals (neuroglobin and cytoglobin) and some cyanobacteria, where they are thought to play a role in free radical scavenging or ligand, sensing. The plant hxHbs can be distinguished from the others because they, are only weakly hexcacoordinate in the ferrous state, yet no structural, mechanism for regulating hexacoordination has been articulated to account, for this behavior. Plant hxHbs contain a conserved Phe at position B10, (Phe(B10)), which is near the reversibly coordinated distal His(E7). We, have investigated the effects of Phe(B10) mutation on kinetic and, equilibrium constants for hexacoordination and exogenous ligand binding in, the ferrous and ferric oxidation states. Kinetic and equilibrium constants, for hexacoordination and ligand binding along with CO-FTIR spectroscopy, midpoint reduction potentials, and the crystal structures of two key, mutant proteins (F40W and F40L) reveal that Phe(B10) is an important, regulatory element in hexacoordination. We show that Phe at this position, is the only amino acid that facilitates stable oxygen binding to the, ferrous Hb and the only one that promotes ligand binding in the ferric, oxidation states. This work presents a structural mechanism for regulating, reversible intramolecular coordination in plant hxHbs.
<StructureSection load='2gnw' size='340' side='right'caption='[[2gnw]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2gnw]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Oryza_sativa Oryza sativa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GNW OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2GNW 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]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</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=2gnw FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2gnw OCA], [https://pdbe.org/2gnw PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2gnw RCSB], [https://www.ebi.ac.uk/pdbsum/2gnw PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2gnw ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NSHB1_ORYSJ NSHB1_ORYSJ] Phytoglobin that reduces nitrite to nitric oxide under anoxic conditions (e.g. during flooding or in waterlogged soil) (PubMed:21495624). May not function as an oxygen storage or transport protein (PubMed:17540516, PubMed:9390447). Has an unusually high affinity for O(2) through a hexacoordinate heme iron because of a very low dissociation constant (PubMed:9390447).<ref>PMID:21495624</ref> <ref>PMID:9390447</ref> <ref>PMID:17540516</ref>
== 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/2gnw_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=2gnw ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
All plants contain an unusual class of hemoglobins that display bis-histidyl coordination yet are able to bind exogenous ligands such as oxygen. Structurally homologous hexacoordinate hemoglobins (hxHbs) are also found in animals (neuroglobin and cytoglobin) and some cyanobacteria, where they are thought to play a role in free radical scavenging or ligand sensing. The plant hxHbs can be distinguished from the others because they are only weakly hexcacoordinate in the ferrous state, yet no structural mechanism for regulating hexacoordination has been articulated to account for this behavior. Plant hxHbs contain a conserved Phe at position B10 (Phe(B10)), which is near the reversibly coordinated distal His(E7). We have investigated the effects of Phe(B10) mutation on kinetic and equilibrium constants for hexacoordination and exogenous ligand binding in the ferrous and ferric oxidation states. Kinetic and equilibrium constants for hexacoordination and ligand binding along with CO-FTIR spectroscopy, midpoint reduction potentials, and the crystal structures of two key mutant proteins (F40W and F40L) reveal that Phe(B10) is an important regulatory element in hexacoordination. We show that Phe at this position is the only amino acid that facilitates stable oxygen binding to the ferrous Hb and the only one that promotes ligand binding in the ferric oxidation states. This work presents a structural mechanism for regulating reversible intramolecular coordination in plant hxHbs.


==About this Structure==
Role of phenylalanine B10 in plant nonsymbiotic hemoglobins.,Smagghe BJ, Kundu S, Hoy JA, Halder P, Weiland TR, Savage A, Venugopal A, Goodman M, Premer S, Hargrove MS Biochemistry. 2006 Aug 15;45(32):9735-45. PMID:16893175<ref>PMID:16893175</ref>
2GNW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Oryza_sativa Oryza sativa] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2GNW OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
Role of phenylalanine B10 in plant nonsymbiotic hemoglobins., Smagghe BJ, Kundu S, Hoy JA, Halder P, Weiland TR, Savage A, Venugopal A, Goodman M, Premer S, Hargrove MS, Biochemistry. 2006 Aug 15;45(32):9735-45. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16893175 16893175]
</div>
<div class="pdbe-citations 2gnw" style="background-color:#fffaf0;"></div>
 
==See Also==
*[[Hemoglobin 3D structures|Hemoglobin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Oryza sativa]]
[[Category: Oryza sativa]]
[[Category: Single protein]]
[[Category: Hoy JA]]
[[Category: Hoy, J.A.]]
[[Category: HEM]]
[[Category: 2 on 2 helical fold]]
[[Category: globin]]
[[Category: heme]]
[[Category: hemoglobin]]
[[Category: hexacoordinate]]
[[Category: iron]]
[[Category: nonsymbiotic]]
[[Category: rice]]
 
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