1z9j
From Proteopedia
(New page: 200px<br /><applet load="1z9j" size="450" color="white" frame="true" align="right" spinBox="true" caption="1z9j, resolution 4.50Å" /> '''Photosynthetic React...) |
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| - | [[Image:1z9j.gif|left|200px]]<br /><applet load="1z9j" size=" | + | [[Image:1z9j.gif|left|200px]]<br /><applet load="1z9j" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1z9j, resolution 4.50Å" /> | caption="1z9j, resolution 4.50Å" /> | ||
'''Photosynthetic Reaction Center from Rhodobacter sphaeroides'''<br /> | '''Photosynthetic Reaction Center from Rhodobacter sphaeroides'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Metals bound to proteins perform a number of crucial biological reactions, including the oxidation of water by a manganese cluster in photosystem II. | + | Metals bound to proteins perform a number of crucial biological reactions, including the oxidation of water by a manganese cluster in photosystem II. Although evolutionarily related to photosystem II, bacterial reaction centers lack both a strong oxidant and a manganese cluster for mediating the multielectron and proton transfer needed for water oxidation. In this study, carboxylate residues were introduced by mutagenesis into highly oxidizing reaction centers at a site homologous to the manganese-binding site of photosystem II. In the presence of manganese, light-minus-dark difference optical spectra of reaction centers from the mutants showed a lack of the oxidized bacteriochlorophyll dimer, while the reduced primary quinone was still present, demonstrating that manganese was serving as a secondary electron donor. On the basis of these steady-state optical measurements, the mutant with the highest-affinity site had a dissociation constant of approximately 1 microM. For the highest-affinity mutant, a first-order rate with a lifetime of 12 ms was observed for the reduction of the oxidized bacteriochlorophyll dimer by the bound manganese upon exposure to light. The dependence of the amplitude of this component on manganese concentration yielded a dissociation constant of approximately 1 muM, similar to that observed in the steady-state measurements. The three-dimensional structure determined by X-ray diffraction of the mutant with the high-affinity site showed that the binding site contains a single bound manganese ion, three carboxylate groups (including two groups introduced by mutagenesis), a histidine residue, and a bound water molecule. These reaction centers illustrate the successful design of a redox active metal center in a protein complex. |
==About this Structure== | ==About this Structure== | ||
| - | 1Z9J is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodobacter_sphaeroides Rhodobacter sphaeroides] with FE, MN, BCL, BPH and U10 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1Z9J is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodobacter_sphaeroides Rhodobacter sphaeroides] with <scene name='pdbligand=FE:'>FE</scene>, <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=BCL:'>BCL</scene>, <scene name='pdbligand=BPH:'>BPH</scene> and <scene name='pdbligand=U10:'>U10</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Z9J OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Rhodobacter sphaeroides]] | [[Category: Rhodobacter sphaeroides]] | ||
| - | [[Category: Allen, J | + | [[Category: Allen, J P.]] |
[[Category: Camara-Artigas, A.]] | [[Category: Camara-Artigas, A.]] | ||
[[Category: Kalman, L.]] | [[Category: Kalman, L.]] | ||
[[Category: Thielges, M.]] | [[Category: Thielges, M.]] | ||
[[Category: Uyeda, G.]] | [[Category: Uyeda, G.]] | ||
| - | [[Category: Williams, J | + | [[Category: Williams, J C.]] |
[[Category: BCL]] | [[Category: BCL]] | ||
[[Category: BPH]] | [[Category: BPH]] | ||
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[[Category: mutant]] | [[Category: mutant]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:13:23 2008'' |
Revision as of 14:13, 21 February 2008
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Photosynthetic Reaction Center from Rhodobacter sphaeroides
Overview
Metals bound to proteins perform a number of crucial biological reactions, including the oxidation of water by a manganese cluster in photosystem II. Although evolutionarily related to photosystem II, bacterial reaction centers lack both a strong oxidant and a manganese cluster for mediating the multielectron and proton transfer needed for water oxidation. In this study, carboxylate residues were introduced by mutagenesis into highly oxidizing reaction centers at a site homologous to the manganese-binding site of photosystem II. In the presence of manganese, light-minus-dark difference optical spectra of reaction centers from the mutants showed a lack of the oxidized bacteriochlorophyll dimer, while the reduced primary quinone was still present, demonstrating that manganese was serving as a secondary electron donor. On the basis of these steady-state optical measurements, the mutant with the highest-affinity site had a dissociation constant of approximately 1 microM. For the highest-affinity mutant, a first-order rate with a lifetime of 12 ms was observed for the reduction of the oxidized bacteriochlorophyll dimer by the bound manganese upon exposure to light. The dependence of the amplitude of this component on manganese concentration yielded a dissociation constant of approximately 1 muM, similar to that observed in the steady-state measurements. The three-dimensional structure determined by X-ray diffraction of the mutant with the high-affinity site showed that the binding site contains a single bound manganese ion, three carboxylate groups (including two groups introduced by mutagenesis), a histidine residue, and a bound water molecule. These reaction centers illustrate the successful design of a redox active metal center in a protein complex.
About this Structure
1Z9J is a Protein complex structure of sequences from Rhodobacter sphaeroides with , , , and as ligands. Full crystallographic information is available from OCA.
Reference
Design of a redox-linked active metal site: manganese bound to bacterial reaction centers at a site resembling that of photosystem II., Thielges M, Uyeda G, Camara-Artigas A, Kalman L, Williams JC, Allen JP, Biochemistry. 2005 May 24;44(20):7389-94. PMID:15895982
Page seeded by OCA on Thu Feb 21 16:13:23 2008
Categories: Protein complex | Rhodobacter sphaeroides | Allen, J P. | Camara-Artigas, A. | Kalman, L. | Thielges, M. | Uyeda, G. | Williams, J C. | BCL | BPH | FE | MN | U10 | Alpha helix | Membrane protein | Mutant
