Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Pushkar, Yulia; Karyagina, Irina; Stehlik, D.; Brown, Sarah; Est, Art van der

doi:10.1074/jbc.m412940200

Cited by 24 publications

(10 citation statements)

References 72 publications

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“…Thus, the electron transfer kinetics of the A 0 to A 1 electron transfer step can be compared in the presence or absence of the F X cluster. The first results of such a comparison are described in the companion paper (36).…”

Section: Discussionmentioning

confidence: 99%

“…In the companion paper (36), it is shown that the more negative redox potential of AQ compared with native PhQ accelerates the A 1 to F X electron transfer kinetics. Correspondingly, the A 0 to A 1 electron transfer step is expected to slow down.…”

Section: Discussionmentioning

confidence: 99%

“…The considerably more biocompatible AQ incorporation into the PS I complexes of the menB rubA mutant offers the opportunity to compare the observed kinetics of electron transfer in the two cases. This comparison is described and evaluated in the accompanying paper (36).…”

Section: -Naphthoquinone (B)mentioning

confidence: 99%

“…6). Note that, compared with the simulated spectrum (dashed line), the measured spectrum (solid line) differs by a net absorptive polarization contribution (additional details are available in the accompanying paper (36)). …”

Section: Flash-induced Absorbance Changes In the Near-ir And Uvmentioning

confidence: 99%

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Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Sakuragi

Zybailov

Shen

et al. 2005

Journal of Biological Chemistry

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A photosystem I (PS I) complex containing plastoquinone-9 (PQ-9) but devoid of F X , F B , and F A was isolated and characterized from a mutant strain of Synechococcus sp. PCC 7002 in which the menB and rubA genes were insertionally inactivated. In isolated PS I trimers, the decay of P700؉ measured in the near-IR and the decay of A 1 ؊ measured in the near-UV were found to be biphasic, with (averaged) room temperature lifetimes of 12 and 350 s. The decay-associated spectra of both kinetic phases are characteristic of the oxidized minus reduced difference spectrum of a semiquinone, consistent with charge recombination between P700؉ and PQ-9 ؊ . The amplitude of the flash-induced absorbance changes in both the near-IR and the near-UV show that approximately one-half of the A 1 binding sites are either empty or nonfunctional. A spin-polarized chlorophyll triplet is observed by time-resolved EPR, and it is attributed to the 3 P700 product of P700 ؉ A 0 ؊ charge recombination via the T 0 spin level in those PS I complexes that do not contain a functional quinone. In those A 1 sites that are occupied, the P700 ؉ Q ؊ polarization pattern indicates that PQ-9 is oriented in a similar manner to that in the menB mutant. When excess 9,10-anthraquinone is added in vitro, it displaces PQ-9 and occupies the A 1 binding site more readily than in the menB mutant. This can be explained by a greater accessibility to the A 1 site in the menB rubA mutant due to the absence of F X and the stromal ridge polypeptides. The relatively low binding affinity of 9,10-anthraquinone allows it to be readily removed from the A 1 site by washing. However, all A 1 sites are shown to bind napthoquinones with high affinity and thus are proven to be functionally competent in quinone binding. The ability to readily displace PQ-9 from the A 1 site makes the menB rubA mutant ideal for introducing novel quinones, particularly anthraquinones, into PS I.Photosystem I is a multisubunit, pigment-protein complex that is found in the membranes of plants, algae, and cyanobacteria and that mediates the light-induced transfer of electrons from plastocyanin/cytochrome c 6 to ferredoxin/flavodoxin. According to current understanding, light-induced charge separation results in the oxidation of the primary electron donor P700 (E m Ј ϩ430 mV), a chlorophyll a/aЈ heterodimer located on the luminal (inner) side of the membrane, and the reduction of the primary electron acceptor A 0 (E m Ј approximately Ϫ1000 mV), a chlorophyll a monomer located in the interior of the membrane. The electron is passed to A 1 (E m Ј approximately Ϫ800 mV), an alkyl-substituted menadione (2-methyl-1,4-naphthalenedione); to F X (E m Ј Ϫ705 mV), an interpolypeptide (4Fe-4S) cluster; and finally to F A (E m Ј Ϫ520 mV) and F B (E m Ј Ϫ580 mV), which are (4Fe-4S) clusters bound to the extrinsic subunit PsaC located on the stromal (cytoplasmic) side of the membrane. In most organisms, including Synechocystis sp. PCC 6803, the quinone in the A 1 site is phylloquinone (2-methyl-3-phytyl-1,4-naphtho...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: -Naphthoquinone (B)mentioning

confidence: 99%

Section: Flash-induced Absorbance Changes In the Near-ir And Uvmentioning

confidence: 99%

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Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Sakuragi

Zybailov

Shen

et al. 2005

Journal of Biological Chemistry

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“…Second, it is known that the spin dynamics during the electron transport generates polarization that is proportional to S. and that this polarization can be analyzed to obtain information about the precursors to the observable RPs [8,[29][30][31][32][33][34][35][36][37][38]. Equation (6) shows that with typical values for the parameters (Aco M < 0.5 mT, d ~ 0.1 mT, J < 10 -3 mT and D M ~ 0.5 mT) the intensity of a singlet-born RP is roughly one to two orders of magnitude less than that of an RP in the S. state.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved EPR spectroscopy of photosynthetic reaction centers: from theory to experiment

Kandrashkin

Est

2007

Appl. Magn. Reson.

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A theoretical description of the electron spin polarization in sequential radical pairs generated by light-induced electron transfer is reviewed and several examples of its application to experimental time-resolved electron paramagnetic resonance from photosynthetic reaction centers are given. It is shown that most of the features of the observed spectra can be understood in terms of basic properties of the radical pairs. The most crucial aspect used in the analysis is that the polarization of the observed radical pairs predominantly inherits the singlet character of the initial excited state of the primary donor. The motion of the spins also generates a small amount of additional polarization during the course of the sequential electron transfer. The theory provides a simple set of mies for qualitative interpretation of experimental data as well asa mathematical model for quantitative simulations of spectra. The comparison of simulated and experimental spectra demonstrates excellent agreement.

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Metal ions in cyanobacterial photosystem I

Biesiadka

Loll

2004

Handbook of Metalloproteins

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Photosystems I (PSI) and photosystem II (PSII) are large multi‐subunit protein–cofactor complexes located in the photosynthetic thylakoid membrane and acting in series. They are fueled by sunlight, PSII oxidizing water to atmospheric O 2 , H + , and electrons that are delivered at the lumenal side of the membrane. The electrons are transferred to PSI where their reducing potential is increased sufficiently to finally produce reduced nicotinamide adenine dinucleotide phosphate (NADPH) at oxidized form of nicotinamide adenine dinucleotide phosphate (NADP + ) reductase while the H + form a gradient across the membrane that drives adenosine triphosphate (ATP‐)synthetase and both, NADPH and ATP, convert CO 2 to carbohydrates in the Calvin cycle. PSI is composed of 12 different protein subunits of which 9 are embedded in the thylakoid membrane and 3 are located on the cytoplasmic (stromal) side of the membrane. Sunlight is absorbed by a large internal antenna composed of 90 chlorophyll a (Chl a ), and the photons are guided to the electron transfer chain (ETC) formed by two symmetry‐related branches where the ‘special pair P 700′ located close to the lumenal side of the membrane is excited and expels an electron to form the cation radical P700 + . The electron is guided from P700 to the stromal side along the ETC consisting of pairs of accessory Chl a , of the primary electron acceptors (Chl a ), of the secondary acceptors phylloquinone (PQ), to the terminal acceptors formed by three Fe 4 S 4 clusters F X , F A , F B . Since each Chl a coordinates one Mg 2+ , PSI harbors a plethora of Mg and Fe cations and one structural Ca 2+ . We describe the coordination of these cations and their function in the photosynthetic process carried out by PSI.

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Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Cited by 24 publications

References 72 publications

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Recruitment of a Foreign Quinone into the A1 Site of Photosystem I

Time-resolved EPR spectroscopy of photosynthetic reaction centers: from theory to experiment

Metal ions in cyanobacterial photosystem I

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