Photoreduction of NADP+ in Photosystem II of Higher Plants: Requirement for Manganese

1992 ◽  
Vol 47 (1-2) ◽  
pp. 57-62 ◽  
Author(s):  
Suleyman I. Allakhverdiev ◽  
Vyacheslav V. Klimov
Keyword(s):  
Photosystem Ii ◽  
Higher Plants ◽  
Complete Removal ◽  
Reaction Centers ◽  
Higher Plant ◽  
Ps Ii ◽  
Alternate Pathway ◽  
Manganese Extraction ◽  
Quinone Acceptor ◽  
Reduced State

Abstract The effects of reversible manganese extraction on NADP+ photoreduction were studied with higher plant subchloroplast preparations of photosystem II (PS II). Under anaerobic conditions, when the reaction centers (RCs) of PS II are “closed” (i.e. in the state [P680 Pheo] QA), and in the presence of ferredoxin-ferredoxin-NADP+ reductase, NADP+ reduction is observed at a rate of 0.8 -1.1 nmol/mg × chlorophyll × h. After complete removal of manganese from PS II, the rate of NADP+ reduction is reduced 40 - 50-fold. Upon the addition of Mn at a concentration of approx. 4 Mn atoms per reaction center, the NADP+ reduction is restored up to 85 -90% of the initial value. When half of this amount of Mn is combined with about 40 times of the equivalent concentration of other divalent ions (Ca2+, Sr2+, Mg2+ etc.) the reaction is also reactivated. Dinoseb (10-6 m) an inhibitor of electron transfer in PS II prevents NADP+ photoreduction. It is concluded that under conditions when the first quinone acceptor, QA, is in its reduced state (QA-) electrons are transferred from reduced pheophytin (Pheo·̅) to NADP+, indicating that PS II can reduce NADP+ without the participation of PS I. On the basis of these and literature data, an alternate pathway for electron phototransfer in PS II reaction centers of higher plants is suggested. Some problems concerning the Z-scheme are discussed.

scholarly journals Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

2021 ◽  
Vol 7 (9) ◽  
pp. 131
Author(s):  
Maria Chrysina ◽  
Georgia Zahariou ◽  
Nikolaos Ioannidis ◽  
Yiannis Sanakis ◽  
George Mitrikas
Keyword(s):  
Electronic Structure ◽  
Photosystem Ii ◽  
Water Oxidation ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Correlation Spectroscopy ◽  
Oxygen Evolving Complex ◽  
Higher Plant ◽  
Proton Coupled Electron Transfer ◽  
S Oxidation

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn4Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (YZ) and D2-Tyr160 (YD) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. YZ of PSII is near the OEC and mediates electron coupled proton transfer from Mn4Ca to the photooxidizable chlorophyll species P680+. YD does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of YD• radical has been extensively characterized only in spinach (Spinacia oleracea) Mn- depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of YD• radical. The hyperfine couplings of the protons that interact with the YD• radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent for the integrity of membrane protein complexes. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of Photosystem II photoactivation.

Q a Binding to D2 Contributes to the Functional and Structural Integrity of Photosystem II

1990 ◽  
Vol 45 (5) ◽  
pp. 359-365 ◽  
Author(s):  
Wim Vermaas ◽  
Jeroen Charité ◽  
Gaozhong Shen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Binding Site ◽  
Structural Integrity ◽  
Reaction Centers ◽  
Ps Ii ◽  
Directed Mutation ◽  
Rapid Inactivation ◽  
Reaction Center Complex ◽  
A Site

Two D2 mutants were created with a site-directed mutation near the presumable binding site of QA. In one of the mutants, in which Trp-253, the aromatic residue potentially involved in facilitating electron transport from pheophytin to QA and/or in binding of Q A, had been replaced by Leu, PS II was undetectable in thylakoids. This mutant is an obligate photoheterotroph. In another mutant the Gly-215 residue, located next to the His residue that is proposed to bind QA and Fe2+, was mutated to Trp. This mutation leads to a rapid inactivation of oxygen evolution capacity in the light, and to a virtual elimination of the potential to grow photoautotrophically, but does not greatly affect the number of photosystem II reaction centers on a chlorophyll basis. We propose that proper binding of QA to the photosystem II reaction center complex is a prerequisite for stability of the photosystem II complex. Impairment of Q a binding leads to rapid inactivation of photosystem II, which may be followed by a structural disintegration of the complex.

The Occurrence of β-Carotene-5,6-epoxide in the Photosynthetic Apparatus of Higher Plants

1989 ◽  
Vol 44 (11-12) ◽  
pp. 959-965 ◽  
Author(s):  
Andrew Young ◽  
Paul Barry ◽  
George Britton
Keyword(s):  
Higher Plants ◽  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Reaction Centre ◽  
Higher Plant ◽  
Ps Ii ◽  
Photooxidative Damage ◽  
Pigment Protein Complexes ◽  
The Individual ◽  
Β Carotene

Abstract The occurrence of β-carotene-5,6-epoxide in higher plant photosynthetic tissue is described. The compound is found in isolated chloroplasts, thylakoids and other subchloroplast particles but can only be detected in intact leaves or cotyledons of higher plants when these are exposed to very high light intensities or to inhibitors such as monuron or paraquat. The distribution of the epoxide within the individual pigment-protein complexes is given. It is particularly associated with the PS I reaction centres (C P I and CP la) and less so with the PS II reaction centre (CPa). Circular dichroism shows that the β-carotene-5,6-epoxide isolated from photosynthetic tissue is optically inactive. It is therefore not produced enzymically but is a product of photooxidative events in the photosynthetic apparatus. Its presence in photosynthetic tissue is a reliable indicator of photooxidative damage to the thylakoid membrane involving oxidation of β-carotene.

Correlation averaging of ordered arrays of Photosystem II

1992 ◽  
Vol 50 (2) ◽  
pp. 1002-1003
Author(s):  
Paul S. Furcinitti ◽  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Structural Information ◽  
Reaction Centers ◽  
Two Dimensional ◽  
Ps Ii ◽  
Bacterial Reaction Centers ◽  
Low Concentrations ◽  
Molecular Masses ◽  
Oxygen Evolving ◽  
Triton X

Photosystem II (PS II) is one of two reaction centers found in the photosynthetic membranes of eukaryotic cells. PS II converts solar to chemical energy and can split water, giving off H+ and O2. Neither bacterial reaction centers nor PS I can evolve O2, making PS II unique. Oxygen evolution involves three polypeptides (17, 24 and 33 kDa) that are exposed on the inner surface of the membrane. The remainder of PS II consists of intrinsic membrane proteins with molecular masses of 47, 43, 34, 33 and 10 kDa and multiple low molecular mass polypeptides (for review, see Hansson and Wydrzynski, 1990). In order to obtain structural information regarding PS II, and particularly the oxygen evolving-polypeptides (OEPs), we have induced the complexes to form two-dimensional crystals. The crystals are formed by sequential treatment of whole membranes with low concentrations of Triton X-100. The two-dimensional crystals are tubular, with the complexes arranged in a helical manner around the tube (Fig. 1). The tubes are being characterized by gel electrophoresis and immunoblotting, using antibodies directed against the OEPs.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent to maintain the integrity of membrane protein complexes. We propose that PsbW and PsbH subunits participate in the phospho-signalling dimerization of the complex, important to the assembly/repair processes of Photosystem II. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of PSII photoactivation.

scholarly journals Exogenously spermidine alleviates damage from drought stress in the photosystem II of tall fescue  

2021 ◽  
Author(s):  
Yu Liu ◽  
Chunxiang Hao ◽  
Guangyang Wang ◽  
Qian Li ◽  
An Shao
Keyword(s):  
Drought Stress ◽  
Photosystem Ii ◽  
Tall Fescue ◽  
Photosynthetic Apparatus ◽  
Crop Productivity ◽  
Protective Role ◽  
Limiting Factors ◽  
Quantum Yields ◽  
Ps Ii ◽  
Quinone Acceptor

Drought stress is one of the major limiting factors to crop productivity around the globe. It has been well documented that spermidine (Spd) plays an important key role in plant growth and development, especially in the defense response to stress. The objective of this study was to explore the effect of Spd on protecting photosynthetic apparatus in tall fescue under drought stress. Spd application significantly improved the OJIP (fluorescence rise kinetics O-J-I-P) curve compared to non-Spd application during drought. Exogenous Spd exhibited higher F<sub>J</sub> (fluorescence value at the J-step (2 ms) of OJIP) and F<sub>P</sub> (maximal recorded fluorescence intensity, at the peak P of OJIP) than non-Spd application. Moreover, normalised total complementary area (S<sub>m</sub>) and the number of Q<sub>A</sub> (primary quinone acceptor of PS II) reduction events (N) significantly reduced after the application of Spd in tall fescue under drought stress. In terms of quantum yields and efficiencies and specific energy fluxes, exogenous Spd notably decreased the values of efficiency of electron transfer from Q<sub>B</sub> (secondary quinone acceptor of PS II) to PSI acceptors (δR<sub>0</sub>), absorption flux per RC (ABS/RC) and trapping flux per RC (TR<sub>0</sub>/RC) compared to the non-Spd application without watering. All the above suggested that exogenous Spd facilitated the photosynthetic system of tall fescue in drought. These observations involved in the electron transport capacity of photosystem II assist in understanding better the protective role of exogenous Spd in tall fescue under drought stress.  

Phenolic Herbicides: Correlation between Lipophilicity and Increased Inhibitory Sensitivity of Thylakoids from Higher Plant Mutants

1986 ◽  
Vol 41 (9-10) ◽  
pp. 881-884 ◽  
Author(s):  
Jörg Durner ◽  
Andreas Thiel ◽  
Peter Böger
Keyword(s):  
Brassica Napus ◽  
Photosystem Ii ◽  
Partition Coefficient ◽  
Inhibitory Activity ◽  
Partition Coefficients ◽  
Higher Plants ◽  
Higher Plant

Abstract Pheonlic herbicides, being quite hydrophilic as compared to classical photosystem-II inhibitors do not exhibit a correlation between inhibitory activity and partition coefficient. Sensitivity against phenolic herbicides, however, as observed with atrazine-resistant thylakoids from higher plants mutants (Brassica napus) is increased by higher partition coefficients.

scholarly journals Two-dimensional crystals of photosystem II: biochemical characterization, cryoelectron microscopy and localization of the D1 and cytochrome b559 polypeptides.

1996 ◽  
Vol 132 (5) ◽  
pp. 823-833 ◽  
Author(s):  
K M Marr ◽  
D N Mastronarde ◽  
M K Lyon
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Photosystem Ii ◽  
Reaction Center ◽  
Biochemical Characterization ◽  
Higher Plants ◽  
Unit Cell ◽  
Two Dimensional ◽  
Cytochrome B559 ◽  
Ps Ii

Photosystem II (PS II) is a photosynthetic reaction center found in higher plants which has the unique ability to evolve oxygen from water. Several groups have formed two-dimensional PS II crystals or have isolated PS II complexes and studied them by electron microscopy and image analysis. The majority of these specimens have not been well characterized biochemically and have yielded relatively low resolution two-dimensional projection maps with a variety of unit cell sizes. We report the characterization of the polypeptide and lipid content of tubular crystals of PS II. The crystals contain the reaction center core polypeptides D1, D2, cytochrome b559, as well as the chlorophyll-binding polypeptides (CP) CP47, CP43, CP29, CP26, CP24, and CP22. The lipid composition was similar to the lipids found in the stacked portion of thylakoids. We also report a 2.0-nm resolution projection map determined by electron microscopy and image analysis of frozen, hydrated PS II crystals. This projection map includes information on the portion of the complex buried in the lipid bilayer. The unit cell is a dimer with unit vectors of 17.0 and 11.4 nm separated by an angle of 106.6 degrees. In addition, Fab fragments against D1 and cytochrome b559 were used to localize those two polypeptides, and thus the reaction center, within the PS II complex. The results indicate that D1 and cytochrome b559 are found within one of the heaviest densities of the monomeric unit.

Photosystem II Inhibition by Pyran-enamine Derivatives

1993 ◽  
Vol 48 (3-4) ◽  
pp. 163-167
Author(s):  
Koichi Yoneyama ◽  
Yoshihiro Nakajima ◽  
Masaru Ogasawara ◽  
Hitoshi Kuramochi ◽  
Makoto Konnai ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Thylakoid Membranes ◽  
Major Determinant ◽  
Ps Ii ◽  
Structure Activity Relationships ◽  
Structure Activity

Abstract Through the studies on structure-activity relationships of 5-acyl-3-(1-aminoalkylidene)-4-hydroxy-2 H-pyran-2,6(3 H)-dione derivatives in photosystem II (PS II) inhibition, overall lipophilicity of the molecule was found to be a major determinant for the activity. In the substituted N -benzyl derivatives, not only the lipophilicity but also the electronic and steric characters of the substituents greatly affected the activity. Their mode of PS II inhibition seemed to be similar to that of DCMU , whereas pyran-enamine derivatives needed to be highly lipophilic to block the electron transport in thylakoid membranes, which in turn diminished the permeability through biomembranes.

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