18O-Water exchange in photosystem II: Substrate binding and intermediates of the water splitting cycle

Hillier, Warwick; Wydrzynski, Tom

doi:10.1016/j.ccr.2007.09.004

Cited by 137 publications

(183 citation statements)

References 106 publications

(182 reference statements)

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“…4. Hillier and Wydrzynski reported additional data on the resolvable S-state dependence of the substrate exchange rates in untreated spinach thylakoids (Hillier and Wydrzynski 2008). The data reveals that the exchange for one substrate water molecule is resolvable in all S states, i.e.…”

Section: Oxygen Evolving Complexmentioning

confidence: 92%

A Possible Evolutionary Origin for the Mn4 Cluster in Photosystem II: From Manganese Superoxide Dismutase to Oxygen Evolving Complex

Najafpour

2009

Orig Life Evol Biosph

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The recently published X-ray absorption fine structure of photosystem II provides a more detailed architecture of the oxygen-evolving complex (OEC) and the surrounding amino acids. In this paper, a comparison between manganese superoxide dismutase, dinuclear manganese catalase enzymes and the oxygen evolving complex in photosystem II is reported. The author suggests that the development of oxygenic photosynthesis occurred in steps, the first of which involved only one manganese ion (Mn(II)) that oxidized two water molecules to hydrogen peroxide and then oxygen.

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Section: Oxygen Evolving Complexmentioning

confidence: 92%

A Possible Evolutionary Origin for the Mn4 Cluster in Photosystem II: From Manganese Superoxide Dismutase to Oxygen Evolving Complex

Najafpour

2009

Orig Life Evol Biosph

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“…Therefore, the elucidation of the mechanistic role of the Ca 2ϩ ion in the OEC is tightly linked to understanding the mechanism of photosynthetic water splitting. (96,99).…”

mentioning

confidence: 99%

The Basic Properties of the Electronic Structure of the Oxygen-evolving Complex of Photosystem II Are Not Perturbed by Ca2+ Removal

Lohmiller¹,

Cox²,

Su³

et al. 2012

Journal of Biological Chemistry

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“…Such changes would thus decrease the electron density of the Mn 4 ion and modulate the ligand exchange reactions. The increased electron donation from histidine into the Mn 4 ion would be expected to increase the 18 O ligand exchange rates as seen in some model systems (Richens 2005;Hillier & Wydrzynski 2008). However, the results in table 1 and figure 2b show there to be minimal effects on the two substrate water exchange rates when the D1-D170H mutant is compared with WT, with relative differences just outside of the fitting errors.…”

Section: Discussionmentioning

confidence: 89%

“…In terms of water binding and interactions with the Mn 4 metal ion, the non-isosteric mutational change of aspartic acid to histidine is expected to induce some level of electronic perturbation in the coordinated Mn ion. Specifically, a perturbation is predicted to arise from the weaker s-donation character of the Asp oxygen ligands compared with the stronger s-donation from the nitrogen ligand from His (Richens 2005;Hillier & Wydrzynski 2008). Such changes would thus decrease the electron density of the Mn 4 ion and modulate the ligand exchange reactions.…”

Section: Discussionmentioning

confidence: 99%

Investigation of substrate water interactions at the high-affinity Mn site in the photosystem II oxygen-evolving complex

Singh

Debus

Wydrzynski

et al. 2007

Phil. Trans. R. Soc. B

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18O isotope exchange measurements of photosystem II (PSII ) in thylakoids from wild-type and mutant Synechocystis have been performed to investigate binding of substrate water to the highaffinity Mn 4 site in the oxygen-evolving complex (OEC). The mutants investigated were D1-D170H, a mutation of a direct ligand to the Mn 4 ion, and D1-D61N, a mutation in the second coordination sphere. The substrate water 18 O exchange rates for D61N were found to be 0.16G0.02 s K1 and 3.03G0.32 s K1 for the slow and fast phases of exchange, respectively, compared with 0.47G0.04 s K1 and 19.7G1.3 s K1 for the wild-type. The D1-D170H rates were found to be 0.70G0.16 s K1 and 24.4G4.6 s K1 and thus are almost within the error limits for the wild-type rates. The results from the D1-D170H mutant indicate that the high-affinity Mn 4 site does not directly bind to the substrate water molecule in slow exchange, but the binding of non-substrate water to this Mn ion cannot be excluded. The results from the D61N mutation show an interaction with both substrate water molecules, which could be an indication that D61 is involved in a hydrogen bonding network with the substrate water. Our results provide limitations as to where the two substrate water molecules bind in the OEC of PSII.

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18O-Water exchange in photosystem II: Substrate binding and intermediates of the water splitting cycle

Cited by 137 publications

References 106 publications

A Possible Evolutionary Origin for the Mn4 Cluster in Photosystem II: From Manganese Superoxide Dismutase to Oxygen Evolving Complex

A Possible Evolutionary Origin for the Mn4 Cluster in Photosystem II: From Manganese Superoxide Dismutase to Oxygen Evolving Complex

The Basic Properties of the Electronic Structure of the Oxygen-evolving Complex of Photosystem II Are Not Perturbed by Ca2+ Removal

Investigation of substrate water interactions at the high-affinity Mn site in the photosystem II oxygen-evolving complex

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