Differential Inhibition and Rephasing of Photosystem II Electron Acceptor Side by Monohalogenated Acetates of Different Hydrophobicity

1992 ◽  
Vol 47 (9-10) ◽  
pp. 711-716 ◽  
Author(s):  
Chunhe Xu ◽  
Yong Zhu ◽  
Govindjee
Keyword(s):  
Photosystem Ii ◽  
Partition Coefficient ◽  
Reaction Center ◽  
Electron Acceptor ◽  
Inhibitory Activity ◽  
Differential Inhibition ◽  
Ps Ii ◽  
Acceptor Side ◽  
Unusual Effect

We demonstrate here that monohalogenated acetates (MFA , monofluoroacetate; M CA, monochloroacetate; MBA, monobromoacetate) are unique probes of the electron acceptor side of the photosystem II (PS II) reaction center: (1) they differentially inhibit the reoxidation of the reduced primary plastoquinone electron acceptor, QA-, by the secondary plastoquinone electron acceptor QB, and increase the equilibrium [QA-] in the order: MBA ≳ M CA > MFA; and (2) M CA and MBA rephase the PS II electron acceptor side, a rather unusual effect. This results in flash number dependence of [QA-] with maxima at even flashes to change to odd flashes. Furthermore, we demonstrate a correlation between the inhibitory activity of the halogenated acetates with their hydrophobicity (i.e., partition coefficient).

Characterization of bonding interactions of the intermediary electron acceptor in the reaction center of Photosystem II by FTIR spectroscopy

1990 ◽  
Vol 1016 (1) ◽  
pp. 49-54 ◽  
Author(s):  
E. Nabedryk ◽  
S. Andrianambinintsoa ◽  
G. Berger ◽  
M. Leonhard ◽  
W. Mäntele ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Ftir Spectroscopy ◽  
Reaction Center ◽  
Electron Acceptor

Studies about the Mechanism of Herbicidal Interaction with Photosystem II in Isolated Chloroplasts

1979 ◽  
Vol 34 (11) ◽  
pp. 1010-1014 ◽  
Author(s):  
Gernot Renger
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Electron Acceptor ◽  
Functional Organization ◽  
Regulatory Element ◽  
Release Kinetics ◽  
Acceptor Side ◽  
Receptor Sites ◽  
Isolated Chloroplasts

Abstract Based on the functional organization scheme of system-II-electron transport and its modification by different procedures a proteinaceous component enwrapping the redox components (plastoquinone molecules) of the acceptor side (thereby acting as regulatory element) is inferred to be the unique target for herbicidal interaction with system II. This proteinaceous component, which is attacked by trypsin, provides the receptor sites for the herbicides. Studies of the release kinetics in trypsinated chloroplasts of the inhibition of oxygen evolution with K3 [Fe (CN)6] as electron acceptor indicates, that there exists a binding area with different specific subreceptor sites rather than a unique binding site for the various types of inhibitors. Furthermore, trypsination of the proteinaceous component enhances the efficiency of the plastoquinone pool to act as a non-photochemical quencher for excitation energy.

Phosphatidylglycerol Requirement for the Function of Electron Acceptor Plastoquinone QBin the Photosystem II Reaction Center†

Biochemistry ◽  
2002 ◽  
Vol 41 (11) ◽  
pp. 3796-3802 ◽  
Author(s):  
Zoltán Gombos ◽  
Zsuzsanna Várkonyi ◽  
Miki Hagio ◽  
Masayo Iwaki ◽  
László Kovács ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Electron Acceptor

Targeted Deletion Mutagenesis of the β Subunit of Cytochrome b559 Protein Destabilizes the Reaction Center of Photosystem II

1990 ◽  
Vol 45 (5) ◽  
pp. 423-429 ◽  
Author(s):  
Himadri B. Pakrasi ◽  
Karin J. Nyhus ◽  
Howard Granok
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Thylakoid Membranes ◽  
Antenna System ◽  
Β Subunit ◽  
Cyt B ◽  
Synechocystis 6803 ◽  
Cytochrome B559 ◽  
Ps Ii ◽  
Individual Gene

Abstract Oligonucleotide-directed mutagenesis techniques were used to delete the psbF gene, encoding the β subunit of the cytochrom e b559 protein of the photosystem II complex in the cyano­ bacterium, Synechocystis 6803. Cyt b559 is an integral com ponent of PS II complex. However, its precise functional role in PS II remains to be determined. Previously, we created a mutant in which the psbF gene as well as three of its neighbouring genes, psbE , psbL and p sb i were simultaneously deleted from the chrom osom e of Synechocystis 6803 (Pakrasi, Williams and Arntzen, EMBO J. 7, 325 -332 , 1988). This mutant had no PS II activity. However, the role of any one of the four individual gene products could not be determined by studying this mutant. The newly generated mutant, T 256, had only one gene, p sbF , deleted from the genome. This mutant was also impaired in its PS II activities. In addition, it had barely detectable levels of two other protein com ponents, D1 (herbicide binding protein) and D2, of the reaction center of PS II, in its thylakoid membranes. In contrast, two other proteins of PS II, CP47 and CP43 were present in appreciable amounts. Fluorescence spectra (77 K) of the mutant showed the absence of a peak at 695 nm that was previously believed to originate from CP47. In addition, phycobilisomes, the light-harvesting antenna system of PS II, were found to be assembled normally in this mutant. We conclude that the presence of the β subunit of Cyt b559 in the thylakoid membranes is critically important for the assembly of PS II reaction center.

scholarly journals Alteration of photosystem II properties with non-photochemical excitation quenching

2000 ◽  
Vol 355 (1402) ◽  
pp. 1405-1418 ◽  
Author(s):  
A. Laisk ◽  
V. Oja
Keyword(s):  
Photosystem Ii ◽  
Turnover Rate ◽  
Photochemical Quenching ◽  
Ps Ii ◽  
Single Turnover ◽  
Acceptor Side ◽  
Donor And Acceptor ◽  
Inhibitory Type ◽  
Non Photochemical Quenching ◽  
Oxygen Yield

Oxygen yield from single turnover flashes and multiple turnover pulses was measured in sunflower leaves differently pre–illuminated to induce either ‘energy–dependent type’ non–photochemical excitation quenching ( q E ) or reversible, inhibitory type non–photochemical quenching ( q I ). A zirconium O 2 analyser, combined with a flexible gas system, was used for these measurements. Oxygen yield from saturating single turnover flashes was the equivalent of 1.3–2.0 μmol e − m −2 in leaves pre–adapted to low light. It did not decrease when q E quenching was induced by a 1 min exposure to saturating light, but it decreased when pre–illumination was extended to 30–60 min. Oxygen evolution from saturating multiple turnover pulses behaved similarly: it did not decrease with the rapidly induced q E but decreased considerably when exposure to saturating light was extended or O 2 concentration was decreased to 0.4%. Parallel recording of chlorophyll fluorescence and O 2 evolution during multiple turnover pulses, interpreted with the help of a mathematical model of photosystem II (PS II) electron transport, revealed PS II donor and acceptor side resistances. These experiments showed that PS II properties depend on the type of non–photochemical quenching present. The rapidly induced and rapidly reversible q E type (photoprotective) quenching does not induce changes in the number of active PS II or in the PS II maximum turnover rate, thus confirming the antenna mechanism of q E. The more slowly induced but still reversible q I type quenching (photoinactivation) induced a decrease in the number of active PS II and in the maximum PS II turnover rate. Modelling showed that, mainly, the acceptor side resistance of PS II increased in parallel with the reversible q I. Oxygen yield from single turnover flashes and multiple turnover pulses was measured in sunflower leaves differently pre–illuminated to induce either ‘energy–dependent type’ non–photochemical excitation quenching ( q E ) or reversible, inhibitory type non–photochemical quenching ( q I ). A zirconium O 2 analyser, combined with a flexible gas system, was used for these measurements. Oxygen yield from saturating single turnover flashes was the equivalent of 1.3–2.0 μmol e − m −2 in leaves pre–adapted to low light. It did not decrease when q E quenching was induced by a 1 min exposure to saturating light, but it decreased when pre–illumination was extended to 30–60 min. Oxygen evolution from saturating multiple turnover pulses behaved similarly: it did not decrease with the rapidly induced q E but decreased considerably when exposure to saturating light was extended or O 2 concentration was decreased to 0.4%. Parallel recording of chlorophyll fluorescence and O 2 evolution during multiple turnover pulses, interpreted with the help of a mathematical model of photosystem II (PS II) electron transport, revealed PS II donor and acceptor side resistances. These experiments showed that PS II properties depend on the type of non–photochemical quenching present. The rapidly induced and rapidly reversible q E type (photoprotective) quenching does not induce changes in the number of active PS II or in the PS II maximum turnover rate, thus confirming the antenna mechanism of q E. The more slowly induced but still reversible q I type quenching (photoinactivation) induced a decrease in the number of active PS II and in the maximum PS II turnover rate. Modelling showed that, mainly, the acceptor side resistance of PS II increased in parallel with the reversible q I.

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