On the Mechanism of the Low-Light Induced Degradation of the D1 Protein: Involvement of Back Electron Transfer in Photosystem II

1995 ◽  
pp. 3263-3266
Author(s):  
N. Keren ◽  
P. J. M. van Kan ◽  
A. Berg ◽  
H. Gong ◽  
S. Shochat ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
D1 Protein ◽  
Low Light ◽  
Back Electron Transfer

Molecular Modelling of the Interaction of Cyanoacrylate Inhibitors with Photosystem II Part 2. The Effect of Stereochemistry of Inhibitor Binding

1993 ◽  
Vol 48 (9-10) ◽  
pp. 782-787 ◽  
Author(s):  
Simon P. Mackay ◽  
Patrick J. O’Malley
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Binding Site ◽  
Energy Minimization ◽  
Electrostatic Interactions ◽  
D1 Protein ◽  
Spatial Arrangement ◽  
Inhibitor Binding ◽  
Protein Residues ◽  
Quinone Binding

Abstract The 2-cyanoacrylate inhibitors are a potent class of herbicides which block electron transfer in photosystem II. The spatial arrangement of different functional groups are an important factor in determining activity and a number of derivatives have been used as stereospecific probes of the secondary quinone binding site. More than one region of stereoselectivity in the binding site has been identified which influences the interaction with specific groups of the inhibitor. We have studied the interaction of various stereoisomers of the cyanoacrylates with the binding site in the D1 protein (residues Leu 210 to Val 280) by determining the nonbonded intermolecular energies between the modelled structures calculated by van der Waals and electrostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain and have found that the results reflect the experimentally determined data

scholarly journals Properties of Photosystem II lacking the PsbJ subunit

2021 ◽  
Author(s):  
alain boussac ◽  
julien sellés ◽  
marion hamon ◽  
miwa sugiura
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Energy Gap ◽  
Donor Side ◽  
Low Light ◽  
Time Resolved ◽  
Uv Visible ◽  
Assembly Intermediate ◽  
Α Helix ◽  
Oxygen Evolving

Photosystem II (PSII), the oxygen-evolving enzyme, consists of 17 trans-membrane and 3 extrinsic membrane proteins. Other subunits bind to PSII during assembly, like Psb27, Psb28, Tsl0063. The presence of Psb27 has been proposed (Zabret et al. 2021; Huang et al. 2021; Xiao et al. 2021) to prevent the binding of PsbJ, a single transmembrane α-helix close to the quinone QB binding site. Consequently, a PSII rid of Psb27, Psb28 and Tsl0034 prior to the binding of PsbJ would logically correspond to an assembly intermediate. The present work describes experiments aiming at further characterizing such a ΔPsbJ-PSII, purified from the thermophilic Thermosynechococcus elongatus, by means of MALDI-TOF spectroscopy, Thermoluminescence, EPR spectroscopy and UV-visible time-resolved spectroscopy. In the purified ΔPsbJ-PSII, an active Mn4CaO5 cluster is present in 60-70 % of the centers. In these centers, although the forward electron transfer seems not affected, the Em of the QB/QB- couple increases by ≈120 mV thus disfavoring the electron coming back on QA. The increase of the energy gap between QA/QA- and QB/QB- could contribute in a protection against the charge recombination between the donor side and QB-, identified at the origin of photoinhibition under low light (Keren et al. 1997), and possibly during the slow photoactivation process.

Photoinactivation and recovery of photosystem II in Chenopodium album leaves grown at different levels of irradiance and nitrogen availability

2002 ◽  
Vol 29 (7) ◽  
pp. 787 ◽  
Author(s):  
Masaharu C. Kato ◽  
Kouki Hikosaka ◽  
Tadaki Hirose
Keyword(s):  
Photosystem Ii ◽  
Protein Turnover ◽  
Nitrogen Availability ◽  
Photosynthetic Capacity ◽  
Chenopodium Album ◽  
D1 Protein ◽  
High Light ◽  
High Nitrogen ◽  
Low Light ◽  
Low Nitrogen

Involvement of photosynthetic capacity and D1 protein turnover in the susceptibility of photosystem II (PSII) to photoinhibition was investigated in leaves of Chenopodium album L. grown at different combinations of irradiance and nitrogen availability: low light and high nitrogen (LL-HN); high light and low nitrogen (HL-LN); and high light and high nitrogen (HL-HN). To test the importance of photosynthetic capacity in the susceptibility to photoinhibition, we adjusted growth conditions so that HL-HN plants had the highest photosynthetic capacity, while that of LL-HN and HL-LN plants was lower but similar to each other. Photoinhibition refers here to net inactivation of PSII determined by the balance between gross inactivation (photoinactivation) and concurrent recovery of PSII via D1 protein turnover. Leaves were illuminated both in the presence and absence of lincomycin, an inhibitor of chloroplast-encoded protein synthesis. Susceptibility to photoinhibition was much higher in plants grown in low light (LL-HN) than those grown in high light (HL-HN and HL-LN). Susceptibility to photoinhibition was similar in HL-LN and HL-HN plants, suggesting that higher photosynthetic energy consumption alone did not mitigate photoinhibition. Experiments with and without lincomycin showed that high-light-grown plants had a lower rate of photoinactivation and a higher rate of concurrent recovery, and that these rates were not influenced by nitrogen availability. These results indicate that turnover of D1 protein plays a crucial role in photoprotection in high-light-grown plants, irrespective of nitrogen availability. For low-nitrogen-grown plants, higher light energy dissipation by other mechanisms may have compensated for lower energy utilization by photosynthesis.

scholarly journals Mechanism of photosystem II photoinactivation and D1 protein degradation at low light: The role of back electron flow

1997 ◽  
Vol 94 (4) ◽  
pp. 1579-1584 ◽  
Author(s):  
N. Keren ◽  
A. Berg ◽  
P. J. M. van Kan ◽  
H. Levanon ◽  
I. Ohad
Keyword(s):  
Photosystem Ii ◽  
Protein Degradation ◽  
Electron Flow ◽  
D1 Protein ◽  
Low Light

Conserved Kinetics at the Reducing Side of Reaction-Center II in Photosynthetic Organisms; Changed Kinetics in Triazine-Resistant Weeds

1990 ◽  
Vol 45 (5) ◽  
pp. 441-445 ◽  
Author(s):  
Marcel A. K. Jansen ◽  
Klaus Pfister
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Decay Time ◽  
D1 Protein ◽  
Structural Variations ◽  
Ecological Fitness ◽  
Photosynthetic Organisms ◽  
Single Turnover ◽  
Functional Factors ◽  
Kinetics Of

The decay of chlorophyll variable fluorescence after a “single turnover” flash is generally assumed to represent the reoxidation of the reduced quinone Qa. We have observed that the kinetics of this decay are very similar in a wide variety of species. Comparing 28 different species, we found an average half decay time of 314 ± 46 μsec. No systematic correlations were found between the decay rate and biochemical or physiological specializations such as C2, C4 or CAM. This indicates that structural as well as functional factors controlling photosystem II electron transfer between Qa and Qb are highly conserved. Apparently, the freedom for natural structural variations in this region is very limited. Triazine resistant plants, characterized by an altered amino acid sequence of the D1 protein, have clearly decreased rates of Qa/Qb electron transfer. We found an average half decay time of 946 ± 100 (isec (5 species). However, this three-fold decrease is much less than previously reported. Therefore, if alterations of photosystem II electron transfer efficiency contributes to an often reported reduction of “ecological fitness”, this contribution is smaller than was hitherto assumed.

On the Mechanisms for the Photoinhibition of the Electron Transfer and the Light Induced Degradation of the D1 Protein in Photosystem II

1990 ◽  
pp. 1309-1316
Author(s):  
Stenbjörn Styring ◽  
Caroline Jegerschöld ◽  
Ivar Virgin ◽  
Anders Ehrenberg ◽  
Bertil Andersson
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
D1 Protein

Electron transfer sensitized photolysis of 'onium salts

1988 ◽  
Vol 66 (2) ◽  
pp. 319-324 ◽  
Author(s):  
R. J. DeVoe ◽  
M. R. V. Sahyun ◽  
Einhard Schmidt ◽  
N. Serpone ◽  
D. K. Sharma
Keyword(s):  
Electron Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Quantitative Model ◽  
Intersystem Crossing ◽  
Single Electron Transfer ◽  
Onium Salts ◽  
Encounter Complex ◽  
Back Electron Transfer

We have studied the anthracene-sensitized photolyses of both diphenyliodonium and triphenylsulphonium salts in solution using both steady-state and laser flash photolysis techniques. Photoproducts, namely, phenylated anthracenes along with iodobenzene or diphenylsulphide, respectively, are obtained from both salts with quantum efficiencies of ca. 0.1 at 375 nm. We infer the intermediacy of diphenyliodo and triphenylsulphur radicals formed by single electron transfer from the singlet-excited anthracene. We have developed a quantitative model of this chemistry, and identify the principal sources of inefficiency as back electron transfer, which occurs at nearly the theoretically limiting rate, intersystem crossing from the initially formed sensitizer–'onium salt encounter complex, and in-cage radical recombination.

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