Sucrose and Glycerol Effects on Photosystem II

Halverson, Kelly M.; Barry, Bridgette A.

doi:10.1016/s0006-3495(03)74566-4

Cited by 23 publications

(35 citation statements)

References 55 publications

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“…The natural abundance spectrum (Fig. 4A) is similar to S 2 Q B Ϫ -minus-S 1 Q B data reported previously (32,33,(35)(36)(37). Fig.…”

Section: Isotopic Labeling and Structural Changes In Mspsupporting

confidence: 85%

“…Whereas many spectral features are in common, when the 200 K and the 277 K spectra are compared, the 200 and 277 K spectra show some dissimilarity in the 1500 -1200 cm Ϫ1 region. The origin of these spectral differences has been discussed previously (35,36). Assignments of the 200 K spectra, based on global isotopic labeling and site-directed mutagenesis, have been described (25,29,47,51).…”

Section: Discussionmentioning

confidence: 99%

“…FT-IR Spectroscopy at 277 K-Infrared spectra at 277 K were recorded on a Bruker (Billerica, MA) IFS-66v/S FT-IR spectrometer equipped with a liquid nitrogen-cooled MCT detector and a Harrick (Ossining, NY) temperature controller (35,36). A Happ-Genzel apodization function and four levels of zero filling were used.…”

Section: Methodsmentioning

confidence: 99%

“…3B may be due to the low amount of label scrambling from Asp to Glu in the [ 13 C]Asp/ Asn-labeled samples (Table I). Infrared Spectroscopy at 277 K-PSII samples, reconstituted with labeled MSP, were irradiated with a single laser flash and examined at 277 K. In these FT-IR experiments, a S 2 Q B Ϫ -minus-S 1 Q B spectrum is acquired (35)(36)(37). The spectra shown in Fig.…”

Section: Isotopic Labeling and Structural Changes In Mspmentioning

confidence: 99%

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Specific Isotopic Labeling and Photooxidation-linked Structural Changes in the Manganese-stabilizing Subunit of Photosystem II

Sachs

Halverson

Barry

2003

Journal of Biological Chemistry

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Photosystem II (PSII) oxidizes water to molecular oxygen; the catalytic site is a cluster of four manganese ions. The catalytic site undergoes four sequential lightdriven oxidation steps to form oxygen; these sequentially oxidized states are referred to as the S n states, where n refers to the number of oxidizing equivalents stored. The extrinsic manganese stabilizing protein (MSP) of PSII influences the efficiency and stability of the manganese cluster, as well as the rates of the S state transitions. To understand how MSP influences photosynthetic water oxidation, we have employed isotope editing and difference Fourier transform infrared spectroscopy. MSP was expressed in Escherichia coli under conditions in which MSP aspartic and glutamic acid residues label at yields of 65 and 41%, respectively. Asparagine and glutamine were also labeled by this approach. GC/MS analysis was consistent with minimal scrambling of label into other amino acid residues and with no significant scrambling into the peptide bond. Selectively labeled MSP was then reconstituted to PSII, which had been stripped of native MSP. Difference Fourier transform infrared spectroscopy was used to probe the S 1 Q A to S 2 Q A ؊ transition at 200 K, as well as the S 1 Q B to S 2 Q B ؊ transition at 277 K. These experiments show that aspargine, glutamine, and glutamate residues in MSP are perturbed by photooxidation of manganese during the S 1 to S 2 transition. Photosystem II (PSII)1 is the multisubunit membrane protein responsible for the light-driven oxidation of water to molecular oxygen in higher plants, algae, and cyanobacteria (1). PSII contains multiple protein subunits, most of which are hydrophobic and traverse the membrane. Intrinsic PSII proteins ligate the antenna and the reaction center chlorophylls, as well as other cofactors that take part in the oxidation/ reduction reactions (2). These intrinsic subunits include the chlorophyll a-binding proteins, CP47 and CP43, the ␣ and ␤ subunits of cytochrome b 559 , and the polypeptides known as D1 and D2. D1 and D2 form the heterodimeric core of PSII (3-5).The catalytic site of the oxygen-evolving complex contains a cluster of four manganese atoms. As water is oxidized, the manganese cluster cycles through five oxidation states, called the S n states (6). Water oxidation is initiated by excitation of the primary chlorophyll donor, P 680 . P 680 * transfers an electron to pheophytin, which in turn reduces a bound plastoquinone, called Q A . Q A Ϫ reduces a second quinone, Q B . Q B acts as a two-electron and two-proton acceptor. On the donor side of PSII, P 680 ϩ oxidizes a redox active tyrosine, Z, which in turn oxidizes the catalytic site. Redox tyrosine Y D and a chlorophyll, Chl Z , are alternate electron donors to P 680 ϩ . Four sequential photooxidations are required for oxygen production (reviewed in Ref. 1).PSII contains several extrinsic subunits, which are bound to the inner lumenal surface of the reaction center (reviewed in Ref. 7). The extrinsic subunits of PSII play key roles in...

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“…The natural abundance spectrum (Fig. 4A) is similar to S 2 Q B Ϫ -minus-S 1 Q B data reported previously (32,33,(35)(36)(37). Fig.…”

Section: Isotopic Labeling and Structural Changes In Mspsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Isotopic Labeling and Structural Changes In Mspmentioning

confidence: 99%

See 2 more Smart Citations

Specific Isotopic Labeling and Photooxidation-linked Structural Changes in the Manganese-stabilizing Subunit of Photosystem II

Sachs

Halverson

Barry

2003

Journal of Biological Chemistry

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“…Second, sucrose is only used in PSII buffers as a cryoprotectant and to improve PSII stability. Finally, at up to 1.3 M, sucrose increases the O 2 -evolution rate in both intact PSII and NaCl-washed PSII by more then 30% (see Halverson and Barry 2003). Table 2 also shows that the substitution of phosphate for MES buffer had little effect on the rate of DCIP reduction.…”

Section: Resultsmentioning

confidence: 88%

Decoupling of the processes of molecular oxygen synthesis and electron transport in Ca2+-depleted PSII membranes

et al. 2008

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Extraction of Ca(2+) from the O(2)-evolving complex (OEC) of photosystem II (PSII) membranes with 2 M NaCl in the light (PSII(-Ca/NaCl)) results in 90% inhibition of the O(2)-evolution reaction. However, electron transfer from the donor to acceptor side of PSII, measured as the reduction of the exogenous acceptor 2,6-dichlorophenolindophenol (DCIP) under continuous light, is inhibited by only 30%. Thus, calcium extraction from the OEC inhibits the synthesis of molecular O(2) but not the oxidation of a substrate we term X, the source of electrons for DCIP reduction. The presence of electron transfer across PSII(-Ca/NaCl) membranes was demonstrated using fluorescence induction kinetics, a method that does not require an artificial acceptor. The calcium chelator, EGTA (5 mM), when added to PSII(-Ca/NaCl) membranes, does not affect the inhibition of O(2) evolution by NaCl but does inhibit DCIP reduction up to 92% (the reason why electron transport in Ca(2+)-depleted materials has not been noticed before). Another chelator, sodium citrate (citrate/low pH method of calcium extraction), also inhibits both O(2) evolution and DCIP reduction. The role of all buffer components (including bicarbonate and sucrose) as possible sources of electrons for PSII(-Ca/NaCl) membranes was investigated, but only the absence of chloride anions strongly inhibited the rate of DCIP reduction. Substitution of other anions for chloride indicates that Cl(-) serves its well-known role as an OEC cofactor, but it is not substrate X. Multiple turnover flash experiments have shown a period of four oscillations of the fluorescence yield (both the maximum level, F(max), and the fluorescence level measured 50 s after an actinic flash in the presence of DCMU) in native PSII membranes, reflecting the normal function of the OEC, but the absence of oscillations in PSII(-Ca/NaCl) samples. Thus, PSII(-Ca/NaCl) samples do not evolve O(2) but do transfer electrons from the donor to acceptor sides and exhibit a disrupted S-state cycle. We explain these results as follows. In Ca(2+)-depleted PSII membranes, obtained without chelators, the oxidation of the OEC stops after the absorption of three quanta of light (from the S1 state), which should convert the native OEC to the S4 state. An one-electron oxidation of the water molecule bound to the Mn cluster then occurs (the second substrate water molecule is absent due to the absence of calcium), and the OEC returns to the S3 state. The appearance of a sub-cycle within the S-state cycle between S3-like and S4-like states supplies electrons (substrate X is postulated to be OH(-)), explains the absence of O(2) production, and results in the absence of a period of four oscillation of the normal functional parameters, such as the fluorescence yield or the EPR signal from S2. Chloride anions probably keep the redox potential of the Mn cluster low enough for its oxidation by Y(Z)(*).

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Influence of osmolytes on the stability of thylakoid‐based dye‐sensitized solar cells

et al. 2019

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Summary In recent years, there has been considerable interest in incorporating naturally occurring components of the photosynthetic apparatus into man‐made solar cells, because of the high quantum efficiency of photosynthetic reaction centers. One hurdle to overcome regarding the use of native membranes in these devices is their limited lifespans. In this study, we used stabilizers to increase the long‐term viability of biomolecules in vitro, thereby alleviating this challenge. In this regard, it is known that osmolytes, such as glycine betaine (GB) and sucrose, preserve photosynthetic activity in isolated photosystems. Upon investigation of the thermal protection properties of GB and sucrose in thylakoid‐based dye‐sensitized solar cells, we report that the addition of GB and sucrose to the thylakoid photosensitizer maintains nonzero photocurrent in the thylakoid‐based solar cell upon heating to 50°C. At 50°C, the GB‐containing cell displayed about a fourfold increase in photocurrent than the control cell, in which the photocurrent was decreased to nearly zero. The addition of 0.5M and 1M sucrose has respectively caused nearly 40% and 70% increases in photoinduced electron transfer activity over the control at 35°С. Similarly, though to a lesser extent, 1M GB caused an approximate 40% increase in electron transfer activity as well. Moving forward, this approach will be extended to alternative membrane protein isolation strategies, allowing for an accurate comparison with traditional detergent‐isolated complexes, with the ultimate goal of developing a cost‐effective and sustainable solar cell.

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Sucrose and Glycerol Effects on Photosystem II

Cited by 23 publications

References 55 publications

Specific Isotopic Labeling and Photooxidation-linked Structural Changes in the Manganese-stabilizing Subunit of Photosystem II

Specific Isotopic Labeling and Photooxidation-linked Structural Changes in the Manganese-stabilizing Subunit of Photosystem II

Decoupling of the processes of molecular oxygen synthesis and electron transport in Ca2+-depleted PSII membranes

Influence of osmolytes on the stability of thylakoid‐based dye‐sensitized solar cells

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