Time resolved EPR on photosystem II particles after irreversible and reversible inhibition of water cleavage with high concentrations of acetate

Bock, Christian; Gerken, S.; Stehlik, D.; Witt, H. T.

doi:10.1016/0014-5793(88)80885-8

Cited by 23 publications

(17 citation statements)

References 21 publications

(9 reference statements)

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“…Binding of acetate (and formate) within the WOC was shown to slow the Y Z • reduction kinetics. Especially the S 2 Y Z • fi S 3 Y Z transition is slowed significantly at room temperature so that the S 2 Y Z • state can be traped (Bock et al 1988;Dorlet et al 1998Dorlet et al , 1999Feyziev et al 2000;Force et al 1997;Kühne et al 1999;Lakshmi et al 1999;Lydakis-Simantiris et al 1998;Maclachlan and Nugent 1993;Szalai and Brudvig 1996a, b;Wincencjusz et al 1996Wincencjusz et al , 1999. Both phenomena can give rise to higher-miss parameters and the current study does not allow deciding, which effect is dominating under our conditions.…”

Section: Effects Of Formate and Acetatementioning

confidence: 47%

“…Extensive experimental work by many laboratories has established that there are at least two binding sites for these carboxylic acids within PSII: one at the non-heme iron (Deligiannakis et al 1994;Diner and Petrouleas 1990;Jajoo et al 2005;Kühne et al 1999;Nugent et al 1992;Wydrzynski and Govindjee 1975;Xiong et al 1997Xiong et al , 1998 and one between Y Z and the Mn 4 O x Ca cluster (Bock et al 1988;Clemens et al 2002;Dorlet et al 1998Dorlet et al , 1999Feyziev et al 2000;Force et al 1997;Govindjee et al 1997;Jajoo et al 2005Jajoo et al , 2006Klimov et al 1995a, b;Kühne et al 1999;Lakshmi et al 1999;Lydakis-Simantiris et al 1998;Maclachlan and Nugent 1993;Mende and Wiessner 1985;Saygin et al 1986;Szalai and Brudvig 1996a, b;Wincencjusz et al 1996Wincencjusz et al , 1999. In three further studies also formate binding near Y D is reported (Hienerwadel et al 1996(Hienerwadel et al , 2005Kim and Barry 1998).…”

Section: Effects Of Formate and Acetatementioning

confidence: 98%

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Interactions of photosystem II with bicarbonate, formate and acetate

Shevela¹,

Klimov

Messinger³

2007

Photosynth Res

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In this study, we probe the effects of bicarbonate (hydrogencarbonate), BC, removal from photosystem II in spinach thylakoids by measuring flash-induced oxygen evolution patterns (FIOPs) with a Joliot-type electrode. For this we compared three commonly employed methods: (1) washing in BC-free medium, (2) formate addition, and (3) acetate addition. Washing of the samples with buffers depleted of BC and CO2 by bubbling with argon (Method 1) under our conditions leads to an increase in the double hit parameter of the first flash (beta 1), while the miss parameter and the overall activity remain unchanged. In contrast, addition of 40-50 mM formate or acetate results in a significant increase in the miss parameter and to an approximately 50% (formate) and approximately 10% (acetate) inhibition of the overall oxygen evolution activity, but not to an increased beta 1 parameter. All described effects could be reversed by washing with formate/acetate free buffer and/or addition of 2-10 mM bicarbonate. The redox potential of the water-oxidizing complex (WOC) in samples treated by Method 1 is compared to samples containing 2 mM bicarbonate in two ways: (1) The lifetimes of the S0, S2, and S3 states were measured, and no differences were found between the two sample types. (2) The S1, S0, S(-1), and S(-2) states were probed by incubation with small concentrations of NH2OH. These experiments displayed a subtle, yet highly reproducible difference in the apparent Si/S(-i) state distribution which is shown to arise from the interaction of BC with PSII in the already reduced states of the WOC. These data are discussed in detail by also taking into account the CO2 concentrations present in the buffers after argon bubbling and during the measurements. These values were measured by membrane-inlet mass spectrometry (MIMS).

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Section: Effects Of Formate and Acetatementioning

confidence: 47%

Section: Effects Of Formate and Acetatementioning

confidence: 98%

Interactions of photosystem II with bicarbonate, formate and acetate

Shevela¹,

Klimov

Messinger³

2007

Photosynth Res

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“…As a result of this work, it has been shown that the difference spectrum of the oxidation of Zrcs is the same as that for oxidation of the immediate donor to Chl aIf in 02-evolving complexes, indicating that the latter is also a tyrosine. Recently, Bock et al [36] reported on an EPR spectrum in PS II complexes where 02 evolution was inactivated by acetate, but completely reversible. From the result it was suggested that the immediate donor to Chl ah in 02-evolving PS II complexes might be a tyrosine.…”

Section: Methodsmentioning

confidence: 99%

Optical characterization of the immediate electron donor to chlorophyll a⁺_II in O₂‐evolving photosystem II complexes Tyrosine as possible electron carrier between chlorophyll a_II and the water‐oxidizing manganese complex

et al. 1988

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The number and chemical nature of the electron carrier(s) between Chl or, and the water-oxidizing enzyme, S, were analyzed through flash-induced absorption changes in the UV with nanosecond time resolution. (i) At all wavelengths where the reaction of the donor with Chl a;, has been characterized, this donor is oxidized in the nanosecond time range in exact accordance with the reduction kinetics of Chl a& The donor is in turn re-reduced with tliz> 10 ps, i.e. in the range where S is oxidized. From this time course it is concluded that there exists only one electron carrier between Chl n:r and S. (ii) The UV-difference spectrum due to the electron transfer from the immediate donor to Chl aI, in the nanosecond time range in O,-evolving PS II complexes is characterized by a maximum around 260 nm and smaller minimum around 310 nm. This spectrum is identical with that observed for the reaction of the donor with Chl u:I in the microsecond time range in T&treated PS II. Therefore, the donors in both reactions must be of the same chemical nature. (iii) This result, together with the well-established similarity of EPR signal IIr of the oxidized donor in T&-treated PS II to the EPR signal II,, recently assigned to Tyr-160 of the D2 protein of PS II [(1988) Proc. Natl. Acad. Sci. USA 85, 4274301, provides strong evidence that the immediate donor to Chl a;, in water-oxidizing PS II is also a tyrosine. (iv) It is shown that the UV-difference spectra of the oxidation of the immediate donor in O,-evolving as well as that of T&treated PS II complexes are similar to the in vitro difference spectrum of the oxidation of tyrosine in water. This independent result supports the conclusion that the donor is a tyrosine.

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“…The binding of carboxylic acids to or near the non-heme iron alters the g value and shape of the associated Q A - Fe II EPR signal ( , ) and slows the rate of electron transfer from Q A - to Q B (). High concentrations of acetate also impede Q A - -to-Q B electron transfer ( , ), presumably by competing with bicarbonate for an acceptor side binding site ( , ). In addition, acetate-inhibited PSII produces a sharpened and shifted Q A - Fe II EPR signal characteristic of a change in the geometry and/or ligation of the non-heme Fe II ( , ).…”

mentioning

confidence: 99%

Competitive Binding of Acetate and Chloride in Photosystem II

1999

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The binding of chloride and acetate to photosystem II (PSII) was examined to elucidate the mechanism of acetate inhibition. The mode of inhibition was studied, and individual binding sites were assigned by steady-state O2 evolution measurements in correlation with electron paramagnetic resonance (EPR) results. Two binding sites were found for acetate, one chloride-sensitive on the electron donor side and one chloride-insensitive on the electron acceptor side. The respective binding constants were as follows: KCl = 0.5 +/- 0.2 mM (chloride binding to the donor side), KI = 16 +/- 5 mM (acetate binding to the donor side), and KI' = 130 +/- 40 mM (acetate binding to the acceptor side). When acetate was bound to the acceptor side of PSII, 200 K illumination induced a narrowed form of the QA-FeII EPR signal, the yield of which was independent of the chloride concentration. When acetate was bound to the donor side, room-temperature illumination produced the S2YZ* state. EPR measurements showed that both the yield and formation rate of this state increased with acetate concentration. Increasing chloride concentrations slowed the rate of formation of the S2YZ* state, but did not affect the steady-state yield of the S2YZ* state. These findings indicate that the light-induced reactions in acetate-inhibited PSII are modulated by both donor side and acceptor side binding of acetate, while the steady-state yield of the S2YZ* state at the high PSII concentrations used for EPR measurements depends primarily on acceptor side turnover. Our data further support a close proximity of chloride to YZ*, indicating a possible role for chloride in the electron-transfer mechanism at the O2-evolving complex.

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Time resolved EPR on photosystem II particles after irreversible and reversible inhibition of water cleavage with high concentrations of acetate

Cited by 23 publications

References 21 publications

Interactions of photosystem II with bicarbonate, formate and acetate

Interactions of photosystem II with bicarbonate, formate and acetate

Optical characterization of the immediate electron donor to chlorophyll a⁺_II in O₂‐evolving photosystem II complexes Tyrosine as possible electron carrier between chlorophyll a_II and the water‐oxidizing manganese complex

Competitive Binding of Acetate and Chloride in Photosystem II

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Time resolved EPR on photosystem II particles after irreversible and reversible inhibition of water cleavage with high concentrations of acetate

Cited by 23 publications

References 21 publications

Interactions of photosystem II with bicarbonate, formate and acetate

Interactions of photosystem II with bicarbonate, formate and acetate

Optical characterization of the immediate electron donor to chlorophyll a+II in O2‐evolving photosystem II complexes Tyrosine as possible electron carrier between chlorophyll aII and the water‐oxidizing manganese complex

Competitive Binding of Acetate and Chloride in Photosystem II

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Optical characterization of the immediate electron donor to chlorophyll a⁺_II in O₂‐evolving photosystem II complexes Tyrosine as possible electron carrier between chlorophyll a_II and the water‐oxidizing manganese complex