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1dsg

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[[Image:1dsg.jpg|left|200px]]<br /><applet load="1dsg" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1dsg, resolution 2.56&Aring;" />
 
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'''CYTOCHROME C PEROXIDASE H175G MUTANT, IMIDAZOLE COMPLEX AT PH 5, ROOM TEMPERATURE.'''<br />
 
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==Overview==
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==CYTOCHROME C PEROXIDASE H175G MUTANT, IMIDAZOLE COMPLEX AT PH 5, ROOM TEMPERATURE.==
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Replacement of the axial histidine ligand with exogenous imidazole has been accomplished in a number of heme protein mutants, where it often serves to complement the functional properties of the protein. In this paper, we describe the effects of pH and buffer ion on the crystal structure of the H175G mutant of cytochrome c peroxidase, in which the histidine tether between the heme and the protein backbone is replaced by bound imidazole. The structures show that imidazole can occupy the proximal H175G cavity under a number of experimental conditions, but that the details of the interaction with the protein and the coordination to the heme are markedly dependent on conditions. Replacement of the tethered histidine ligand with imidazole permits the heme to shift slightly in its pocket, allowing it to adopt either a planar or distally domed conformation. H175G crystallized from both high phosphate and imidazole concentrations exists as a novel, 5-coordinate phosphate bound state, in which the proximal imidazole is dissociated and the distal phosphate is coordinated to the iron. To accommodate this bound phosphate, the side chains of His-52 and Asn-82 alter their positions and a significant conformational change in the surrounding protein backbone occurs. In the absence of phosphate, imidazole binds to the proximal H175G cavity in a pH-dependent fashion. At pH 7, imidazole is directly coordinated to the heme (d(Fe--Im) = 2.0 A) with a nearby distal water (d(Fe--HOH) = 2.4 A). This is similar to the structure of WT CCP except that the iron lies closer in the heme plane, and the hydrogen bond between imidazole and Asp-235 (d(Im--Asp) = 3.1 A) is longer than for WT CCP (d(His--Asp) = 2.9 A). As the pH is dropped to 5, imidazole dissociates from the heme (d(Fe--Im) = 2.9 A), but remains in the proximal cavity where it is strongly hydrogen bonded to Asp-235 (d(Im--Asp) = 2.8 A). In addition, the heme is significantly domed toward the distal pocket where it may coordinate a water molecule. Finally, the structure of H175G/Im, pH 6, at low temperature (100 K) is very similar to that at room temperature, except that the water above the distal heme face is not present. This study concludes that steric restrictions imposed by the covalently tethered histidine restrain the heme and its ligand coordination from distortions that would arise in the absence of the restricted tether. Coupled with the functional and spectroscopic properties described in the following paper in this issue, these structures help to illustrate how the delicate and critical interactions between protein, ligand, and metal modulate the function of heme enzymes.
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<StructureSection load='1dsg' size='340' side='right'caption='[[1dsg]], [[Resolution|resolution]] 2.56&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1dsg]] is a 1 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=1DSG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1DSG FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.56&#8491;</td></tr>
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<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>, <scene name='pdbligand=IMD:IMIDAZOLE'>IMD</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1dsg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1dsg OCA], [https://pdbe.org/1dsg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1dsg RCSB], [https://www.ebi.ac.uk/pdbsum/1dsg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1dsg ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/CCPR_YEAST CCPR_YEAST] Destroys radicals which are normally produced within the cells and which are toxic to biological systems.
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ds/1dsg_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</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=1dsg ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1DSG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=IMD:'>IMD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Cytochrome-c_peroxidase Cytochrome-c peroxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.11.1.5 1.11.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DSG OCA].
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*[[Cytochrome c peroxidase 3D structures|Cytochrome c peroxidase 3D structures]]
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__TOC__
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==Reference==
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</StructureSection>
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Replacement of the axial histidine ligand with imidazole in cytochrome c peroxidase. 1. Effects on structure., Hirst J, Wilcox SK, Williams PA, Blankenship J, McRee DE, Goodin DB, Biochemistry. 2001 Feb 6;40(5):1265-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11170452 11170452]
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[[Category: Large Structures]]
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[[Category: Cytochrome-c peroxidase]]
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[[Category: Saccharomyces cerevisiae]]
[[Category: Saccharomyces cerevisiae]]
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[[Category: Single protein]]
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[[Category: Goodin DB]]
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[[Category: Goodin, D B.]]
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[[Category: Hirst J]]
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[[Category: Hirst, J.]]
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[[Category: McRee DE]]
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[[Category: McRee, D E.]]
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[[Category: Wilcox SK]]
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[[Category: Wilcox, S K.]]
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[[Category: Williams PA]]
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[[Category: Williams, P A.]]
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[[Category: HEM]]
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[[Category: IMD]]
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[[Category: cavity mutant]]
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[[Category: heme enzyme]]
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[[Category: ligand binding]]
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[[Category: peroxidase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:20:02 2008''
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Current revision

CYTOCHROME C PEROXIDASE H175G MUTANT, IMIDAZOLE COMPLEX AT PH 5, ROOM TEMPERATURE.

PDB ID 1dsg

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