Access channels and methanol binding site to the CaMn4 cluster in Photosystem II based on solvent accessibility simulations, with implications for substrate water access

Ho, Felix M.; Styring, Stenbjörn

doi:10.1016/j.bbabio.2007.08.009

Cited by 154 publications

(223 citation statements)

References 59 publications

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“…An ESEEM study employing 2 H-labeled methanol clearly showed that methanol (and ethanol) binds at-or at least very close to-the Mn 4 O x Ca cluster (Force et al 1998). Consistent with this result it was recently demonstrated by molecular mechanics simulations that an access channel exists that is big enough in diameter to allow methanol (and of cause the smaller water) to diffuse from the lumen to the catalytic Mn 4 O x Ca cluster (Ho and Styring 2008;see, also Murray and Barber 2007).…”

Section: Introductionsupporting

confidence: 60%

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Nöring¹,

Shevela

Ренгер

et al. 2008

Photosynth Res

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From a chemical point of view methanol is one of the closest analogues of water. Consistent with this idea EPR spectroscopy studies have shown that methanol binds at-or at least very close to-the Mn 4 O x Ca cluster of photosystem II (PSII). In contrast, Clark-type oxygen rate measurements demonstrate that the O 2 evolving activity of PSII is surprisingly unaffected by methanol concentrations of up to 10%. Here we study for the first time in detail the effect of methanol on photosynthetic water-splitting by employing a Joliot-type bare platinum electrode. We demonstrate a linear dependence of the miss parameter for S i state advancement on the methanol concentrations in the range of 0-10% (v/v). This finding is consistent with the idea that methanol binds in PSII with similar affinity as water to one or both substrate binding sites at the Mn 4 O x Ca cluster. The possibility is discussed that the two substrate water molecules bind at different stages of the cycle, one during the S 4 ? S 0 and the other during the S 2 ? S 3 transition.

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Section: Introductionsupporting

confidence: 60%

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Nöring¹,

Shevela

Ренгер

et al. 2008

Photosynth Res

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“…A2 (light blue) was assigned at 2.9 resolution, [7] whereas A1 (dark blue) was identified in earlier work. [99,100] B2 was first proposed by Gabdulkhakov et al [16] and becomes a possible channel after conformational change of Lys 134U. 2 + ion by a fatty acid ester carbonyl group (probably mediated by a water molecule).…”

Section: Integral Lipids Of Psiiccmentioning

confidence: 98%

Recent Progress in the Crystallographic Studies of Photosystem II

et al. 2010

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The photosynthetic oxygen-evolving photosystem II (PSII) is the only known biochemical system that is able to oxidize water molecules and thereby generates almost all oxygen in the Earth's atmosphere. The elucidation of the structural and mechanistic aspects of PSII keeps scientists all over the world engaged since several decades. In this Minireview, we outline the progress in understanding PSII based on the most recent crystal structure at 2.9 A resolution. A likely position of the chloride ion, which is known to be required for the fast turnover of water oxidation, could be determined in native PSII and is compared with work on bromide and iodide substituted PSII. Moreover, eleven new integral lipids could be assigned, emphasizing the importance of lipids for the perfect function of PSII. A third plastoquinone molecule (Q(C)) and a second quinone transfer channel are revealed, making it possible to consider different mechanisms for the exchange of plastoquinone/plastoquinol molecules. In addition, possible transport channels for water, dioxygen and protons are identified.

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“…It has been recently demonstrated the water molecule is located between the manganese and chloride ions (Guskov et al , 2010. It has been suggested that different channels within the protein matrix proceed the delivery of substrate water to manganese cluster along with removal of proton and molecular oxygen (Ishikita et al 2006;Murray and Barber 2007;Ho and Styring 2008;Ho 2008;Gabdulkhakov et al 2009). Chloride ion has been proposed to block the channels filled with water molecules and thus restrict the leakage of water molecules out of the channels towards the water-splitting-manganese complex Gabdulkhakov et al 2009).…”

Section: Discussionmentioning

confidence: 97%

Role of chloride ion in hydroxyl radical production in photosystem II under heat stress: Electron paramagnetic resonance spin-trapping study

Yadav

Pospı́šil

2012

J Bioenerg Biomembr

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Hydroxyl radical (HO•) production in photosystem II (PSII) was studied by electron paramagnetic resonance (EPR) spin-trapping technique. It is demonstrated here that the exposure of PSII membranes to heat stress (40 °C) results in HO• formation, as monitored by the formation of EMPO-OH adduct EPR signal. The presence of different exogenous halides significantly suppressed the EMPO-OH adduct EPR signal in PSII membranes under heat stress. The addition of exogenous acetate and blocker of chloride channel suppressed the EMPO-OH adduct EPR signal, whereas the blocker of calcium channel did not affect the EMPO-OH adduct EPR signal. Heat-induced hydrogen peroxide (H₂O₂) production was studied by amplex red fluorescent assay. The presence of exogenous halides, acetate and chloride blocker showed the suppression of H₂O₂ production in PSII membranes under heat stress. Based on our results, it is proposed that the formation of HO• under heat stress is linked to uncontrolled accessibility of water to the water-splitting manganese complex caused by the release of chloride ion on the electron donor side of PSII. Uncontrolled water accessibility to the water-splitting manganese complex causes the formation of H₂O₂ due to improper water oxidation, which leads to the formation of HO• via the Fenton reaction under heat stress.

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Access channels and methanol binding site to the CaMn4 cluster in Photosystem II based on solvent accessibility simulations, with implications for substrate water access

Cited by 154 publications

References 59 publications

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Recent Progress in the Crystallographic Studies of Photosystem II

Role of chloride ion in hydroxyl radical production in photosystem II under heat stress: Electron paramagnetic resonance spin-trapping study

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