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[[ | ==Structure of the imidazole-adduct of the Phormidium laminosum cytochrome c6 Q51V variant== | ||
<StructureSection load='3ph2' size='340' side='right' caption='[[3ph2]], [[Resolution|resolution]] 1.40Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[3ph2]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Phormidium_laminosum Phormidium laminosum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3PH2 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3PH2 FirstGlance]. <br> | |||
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=IMD:IMIDAZOLE'>IMD</scene></td></tr> | |||
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2v08|2v08]]</td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ph2 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3ph2 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3ph2 RCSB], [http://www.ebi.ac.uk/pdbsum/3ph2 PDBsum]</span></td></tr> | |||
</table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
The amino acid at position 51 in the cytochrome c (6) family is responsible for modulating over 100 mV of heme midpoint redox potential. As part of the present work, the X-ray structure of the imidazole adduct of the photosynthetic cytochrome c (6) Q51V variant from Phormidium laminosum has been determined. The structure reveals the axial Met ligand is dissociated from the heme iron but remains inside the heme pocket and the Omega-loop housing the Met ligand is stabilized through polar interactions with the imidazole and heme propionate-6. The latter is possible owing to a 180 degrees rotation of both heme propionates upon imidazole binding. From equilibrium and kinetic studies, a Val residue at position 51 increases the stability of the Fe-S(Met) interaction and also affects the dynamics associated with imidazole binding. In this respect, the k (obs) for imidazole binding to Arabidopsis thaliana cytochrome c (6A), which has a Val at the position equivalent to position 51 in photosynthetic cytochrome c (6), was found to be independent of imidazole concentration, indicating that the binding process is limited by the Met dissociation rate constant (about 1 s(-1)). For the cytochrome c (6) Q51V variant, imidazole binding was suppressed in comparison with the wild-type protein and the V52Q variant of cytochrome c (6A) was found to bind imidazole readily. We conclude that the residue type at position 51/52 in the cytochrome c (6) family is additionally responsible for tuning the stability of the heme iron-Met bond and the dynamic properties of the ferric protein fold associated with endogenous ligand binding. | |||
Structural and kinetic studies of imidazole binding to two members of the cytochrome c (6) family reveal an important role for a conserved heme pocket residue.,Rajagopal BS, Wilson MT, Bendall DS, Howe CJ, Worrall JA J Biol Inorg Chem. 2011 Jan 26. PMID:21267610<ref>PMID:21267610</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
==See Also== | ==See Also== | ||
*[[Cytochrome c|Cytochrome c]] | *[[Cytochrome c|Cytochrome c]] | ||
== References == | |||
== | <references/> | ||
< | __TOC__ | ||
</StructureSection> | |||
[[Category: Phormidium laminosum]] | [[Category: Phormidium laminosum]] | ||
[[Category: Worrall, J A.R | [[Category: Worrall, J A.R]] | ||
[[Category: Class i cytochrome c]] | [[Category: Class i cytochrome c]] | ||
[[Category: Cytochrome f]] | [[Category: Cytochrome f]] | ||
Revision as of 16:35, 9 December 2014
Structure of the imidazole-adduct of the Phormidium laminosum cytochrome c6 Q51V variantStructure of the imidazole-adduct of the Phormidium laminosum cytochrome c6 Q51V variant
Structural highlights
Publication Abstract from PubMedThe amino acid at position 51 in the cytochrome c (6) family is responsible for modulating over 100 mV of heme midpoint redox potential. As part of the present work, the X-ray structure of the imidazole adduct of the photosynthetic cytochrome c (6) Q51V variant from Phormidium laminosum has been determined. The structure reveals the axial Met ligand is dissociated from the heme iron but remains inside the heme pocket and the Omega-loop housing the Met ligand is stabilized through polar interactions with the imidazole and heme propionate-6. The latter is possible owing to a 180 degrees rotation of both heme propionates upon imidazole binding. From equilibrium and kinetic studies, a Val residue at position 51 increases the stability of the Fe-S(Met) interaction and also affects the dynamics associated with imidazole binding. In this respect, the k (obs) for imidazole binding to Arabidopsis thaliana cytochrome c (6A), which has a Val at the position equivalent to position 51 in photosynthetic cytochrome c (6), was found to be independent of imidazole concentration, indicating that the binding process is limited by the Met dissociation rate constant (about 1 s(-1)). For the cytochrome c (6) Q51V variant, imidazole binding was suppressed in comparison with the wild-type protein and the V52Q variant of cytochrome c (6A) was found to bind imidazole readily. We conclude that the residue type at position 51/52 in the cytochrome c (6) family is additionally responsible for tuning the stability of the heme iron-Met bond and the dynamic properties of the ferric protein fold associated with endogenous ligand binding. Structural and kinetic studies of imidazole binding to two members of the cytochrome c (6) family reveal an important role for a conserved heme pocket residue.,Rajagopal BS, Wilson MT, Bendall DS, Howe CJ, Worrall JA J Biol Inorg Chem. 2011 Jan 26. PMID:21267610[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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