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

Gerken, S.; Brettel, Klaus; Schlodder, E.; Witt, H. T.

doi:10.1016/0014-5793(88)80174-1

Cited by 112 publications

(81 citation statements)

References 41 publications

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“…3A) and were unaffected as well (Fig. 3A, lanes [1][2][3][4][5]. However, minor alterations in the R F values of some subunits were observed, especially when the PSII sample was not treated with DTT or treated with DTT following denaturation (compare lanes 1 and 2 with lanes 3-5).…”

Section: The Order Of Addition Affects 14 C Labeling From Methylamine-inmentioning

confidence: 99%

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Probing the Structure of Photosystem II with Amines and Phenylhydrazine

Anderson

Ouellette

Barry

2000

Journal of Biological Chemistry

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-[14 C]butylamine and phenylhydrazine were employed as probes. Neither compound can be oxidized by a transamination or addition/elimination mechanism, but both can react with activated carbonyl groups, produced as a result of posttranslational modification of amino acid residues, to give amine-derived adducts.14 C incorporation into the PSII subunits D2/D1 and CP47 was obtained upon treatment of PSII with either t-[ 14 C]butylamine or [ 14 C]phenylhydrazine. For t-butylamine and methylamine, the amount of labeling increased when PSII was treated with denaturing agents. Labeling of CP47, D2, and D1 with methylamine and phenylhydrazine approached a one-to-one stoichiometry, assuming that D2 and D1 each have one binding site. Evidence was obtained suggesting that reductive stabilization and/or access are modulated by PSII light reactions. These results support the proposal that PSII subunits D2, D1, and CP47 contain quinocofactors and that access to these sites is sterically limited.Photosystem II (PSII), 1 a membrane-bound protein complex, catalyzes the light-driven oxidation of water and the reduction of plastoquinone. PSII consists of hydrophobic and extrinsic subunits and contains chlorophyll, plastoquinone, manganese, and several other bound cofactors. Water oxidation occurs at a manganese-containing catalytic site located on the lumenal side of the membrane. After photoexcitation, the primary chlorophyll donor, P 680 , transfers an electron from its excited state to a pheophytin molecule. Pheophytin transfers the electron to a quinone acceptor molecule, Q A , which in turn reduces a second quinone acceptor, Q B (reviewed in Refs. 1 and 2). PSII contains two well characterized redox-active tyrosines, Z and D (3, 4). Z, an intermediate electron carrier between P 680 and the manganese cluster, reduces oxidized P 680 (5). D forms a stable radical and has no known role in water oxidation (6). Oxidation of a third, posttranslationally modified tyrosine, M, occurs in PSII site-directed mutants (6 -9).Primary amines are known to be substrate analogs and inhibitors of oxygen evolution (10 -12). Recently, the covalent incorporation of 14 C-labeled primary amines into PSII subunits has been observed under reducing conditions (13). Evidence for oxidation of [ 14 C]benzylamine by PSII was obtained by detection and quantitation of [ 14 C]benzaldehyde (13). Because PSII exhibits this amine oxidation activity and an aldehyde product has been observed, covalent incorporation of 14 C from labeled primary amines into PSII subunits could be caused by two possible reactions (13). In the first possible reaction, addition of reductant traps a Schiff base complex of substrate ( 14 C-labeled amine) and an amino acid side chain that has been posttranslationally modified to contain an activated carbonyl group (13,14,15). In the second possible reaction, addition of reductant traps a Schiff base complex of product ( 14 C-labeled aldehyde) and the amino group of a lysine side chain (13). When formaldehyde is produced, this reaction produ...

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Section: The Order Of Addition Affects 14 C Labeling From Methylamine-inmentioning

confidence: 99%

“…PSII contains two well characterized redox-active tyrosines, Z and D (3,4). Z, an intermediate electron carrier between P 680 and the manganese cluster, reduces oxidized P 680 (5). D forms a stable radical and has no known role in water oxidation (6).…”

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confidence: 99%

Probing the Structure of Photosystem II with Amines and Phenylhydrazine

Anderson

Ouellette

Barry

2000

Journal of Biological Chemistry

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“…In turn, tyrosine Y Z ⅐ oxidizes the oxygen-evolving complex (OEC) on every flash ( Fig. 1 A, reaction 5) (8). Four sequential photooxidation reactions are required for oxygen production, and the oxidizing complex cycles among five oxidation states, called the S n states, where n refers to the number of oxidizing equivalents stored (9).…”

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confidence: 99%

Time-resolved vibrational spectroscopy detects protein-based intermediates in the photosynthetic oxygen-evolving cycle

Barry

Cooper²,

Riso³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Photosynthetic oxygen production by photosystem II (PSII) is responsible for the maintenance of aerobic life on earth. The production of oxygen occurs at the PSII oxygen-evolving complex (OEC), which contains a tetranuclear manganese (Mn) cluster. Photo-induced electron transfer events in the reaction center lead to the accumulation of oxidizing equivalents on the OEC. Four sequential photooxidation reactions are required for oxygen production. The oxidizing complex cycles among five oxidation states, called the S n states, where n refers to the number of oxidizing equivalents stored. Oxygen release occurs during the S 3-to-S0 transition from an unstable intermediate, known as the S4 state. In this report, we present data providing evidence for the production of an intermediate during each S state transition. These proteinderived intermediates are produced on the microsecond to millisecond time scale and are detected by time-resolved vibrational spectroscopy on the microsecond time scale. Our results suggest that a protein-derived conformational change or proton transfer reaction precedes Mn redox reactions during the S 2-to-S3 and S 3-to-S0 transitions.manganese cluster ͉ photosynthesis ͉ photosystem II ͉ time-resolved IR ͉ water oxidation T ime-resolved vibrational spectroscopy can detect chemical intermediates formed during enzymatic catalysis. Advantages include the technique's exquisite structural sensitivity and its high temporal resolution. Recent advances in methodology and interpretation have produced insights into the catalytic mechanism in several biological systems (for examples, see refs. 1-4).In this paper, we report the use of time-resolved IR spectroscopy to investigate the mechanism of photosynthetic water oxidation. Photosystem II (PSII) catalyzes the oxidation of water and the reduction of bound plastoquinone. Photoexcitation of PSII leads to the oxidation of the chlorophyll donor, P 680 , and the sequential reduction of a pheophytin (Fig. 1A, reaction 1) and a plastoquinone, Q A ( Fig. 1 A, reaction 2), in picoseconds. Q A reduces Q B to generate a semiquinone radical, Q B Ϫ , on the microsecond time scale (Fig. 1 A, reaction 3 ) (reviewed in ref. 5).A second photoexcitation leads to the reduction and protonation of Q B Ϫ to form the quinol Q B H 2 . The rate of reduction of Q B is faster than the rate of reduction of Q B Ϫ (see ref. 6 and references therein), which gives rise to a characteristic period-2 oscillation in kinetics originating on the PSII acceptor side (7).The primary chlorophyll donor, P 680 , oxidizes a tyrosine, Y Z (Y161 in the D1 subunit), on the nanosecond to microsecond time scale (Fig. 1 A, reaction 4). In turn, tyrosine Y Z ⅐ oxidizes the oxygen-evolving complex (OEC) on every flash (Fig. 1 A, reaction 5) (8). Four sequential photooxidation reactions are required for oxygen production, and the oxidizing complex cycles among five oxidation states, called the S n states, where n refers to the number of oxidizing equivalents stored (9). The rate of OEC oxidation slows as o...

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“…P680 ϩ oxidizes tyrosine 161, Y Z , located on subunit D1 of PS II (4). Y Z is the immediate electron donor to P680 ϩ (5). Y Z ox , in turn, extracts an electron from the water oxidizing complex and catalytic center (CC), respectively (6).…”

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confidence: 99%

Stoichiometry of Proton Release from the Catalytic Center in Photosynthetic Water Oxidation

Schlodder

Witt

1999

Journal of Biological Chemistry

154

137

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The catalytic center (CC) of water oxidation in photosystem II passes through four stepwise increased oxidized states (S 0 -S 4 ) before O 2 evolution takes place from 2H 2 O in the S 4 3 S 0 transition. The pattern of the release of the four protons from the CC cannot be followed directly in the medium, because proton release from unknown amino acid residues also takes place. However, pH-independent net charge oscillations of 0:0:1:1 in S 0 :S 1 :S 2 :S 3 have been considered as an intrinsic indicator for the H ؉ release from the CC. The net charges have been proposed to be created as the charge difference between electron abstraction and H ؉ release from the CC. Then the H ؉ release from the CC is 1:0:1:2 for the S 0 3 S 1 3 S 2 3 S 3 3 S 0 transition. Strong support for this conclusion is given in this work with the analysis of the pH-dependent pattern of H ؉ release in the medium measured directly by a glass electrode between pH 5.5 and 7.2. Improved and crystallizable photosystem II core complexes from the cyanobacterium Synechococcus elongatus were used as material. The pattern can be explained by protons released from the CC with a stoichiometry of 1:0:1:2 and protons from an amino acid group (pK Ϸ 5.7) that is deprotonated and reprotonated through electrostatic interaction with the oscillating net charges 0:0:1:1 in S 0 :S 1 :S 2 :S 3 . Possible water derivatives that circulate through the S states have been named.

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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

Cited by 112 publications

References 41 publications

Probing the Structure of Photosystem II with Amines and Phenylhydrazine

Probing the Structure of Photosystem II with Amines and Phenylhydrazine

Time-resolved vibrational spectroscopy detects protein-based intermediates in the photosynthetic oxygen-evolving cycle

Stoichiometry of Proton Release from the Catalytic Center in Photosynthetic Water Oxidation

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