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Spectroscopic characterization of intermediate steps involved in donor-side-induced photoinhibition of photosystem II

Jegerschold, C and Styring, Stenbjörn LU (1996) In Biochemistry 35(24). p.7794-7801
Abstract
The reaction center protein D1 in photosystem II shows a high turnover during illumination. The degradation of the DI protein is preceded by photoinhibition of the electron transport in photosystem II. There are two distinct mechanisms for this: acceptor-side- and donor-side-induced photoinhibition. Here, donor-side-induced photoinhibition was studied in photosystem II membranes after Cl- depletion or washing with tris(hydroxymethyl)aminomethane (Tris) which destroys water oxidation, reversibly or irreversibly, respectively. Photoinhibition after these treatments leads to fast degradation of the D1 protein, and the mechanism behind this was investigated, Illumination of Cl- depleted photosystem II membranes resulted in a rapid and... (More)
The reaction center protein D1 in photosystem II shows a high turnover during illumination. The degradation of the DI protein is preceded by photoinhibition of the electron transport in photosystem II. There are two distinct mechanisms for this: acceptor-side- and donor-side-induced photoinhibition. Here, donor-side-induced photoinhibition was studied in photosystem II membranes after Cl- depletion or washing with tris(hydroxymethyl)aminomethane (Tris) which destroys water oxidation, reversibly or irreversibly, respectively. Photoinhibition after these treatments leads to fast degradation of the D1 protein, and the mechanism behind this was investigated, Illumination of Cl- depleted photosystem II membranes resulted in a rapid and simultaneous inhibition of Cl--reconstitutable oxygen evolution, loss of 2 Mn ions per photosystem II center, increase in the electron transfer between the electron donor diphenylcarbazide and electron acceptor 2,6-dichlorophenolindophenol, and an increase in the EPR signal IIfast from tyrosine-Z(ox). The destruction of the Mn cluster leads to the loss of oxygen evolution and to an increased accessibility for diphenylcarbazide to donate electrons to Tyr-Z(ox). The increase in the EPR signal from Tyr-Z(ox) can be explained by slower reduction kinetics of Tyr-Z(ox) due to the Mn release. On a longer photoinhibition time scale, a decrease in the amplitude of Tyr-Z(ox) and inhibition of the electron transport from diphenylcarbazide to 2,6-dichlorophenolindophenol occurred simultaneously in both Cl--depleted and Tris-washed photosystem II membranes. These slower photoinhibition reactions were then studied in detail in Tris-washed photosystem II membranes. Compared to photoinhibition of Tyr-Z(ox), the EPR signal from tyrosine-D-ox decreased much slower. Tyr-D-ox was photoinhibited in parallel with the EPRsignals from reduced Q(A), reduced pheophytin, and an oxidized chlorophyll radical (chlorophyll(Z)), This shows that the acceptor side components and the primary charge separation reaction (P680(+) pheophytin(-)) were operational although Tyr-Z was inactivated. The amount of the D1 protein also declined in parallel with Tyr-D-ox, which shows that the D1 protein is not damaged until long after the Mn complex and Tyr-Z have become inactivated. Instead, it is likely that the strongly oxidizing P680(+) is responsible for the damage to the D1 protein. (Less)
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keywords
ACCEPTOR SIDE, OXIDIZING SIDE, RESONANCE SIGNAL-II, REACTION CENTER PROTEIN, SYNECHOCYSTIS SP PCC-6803, SPINACH THYLAKOID MEMBRANES, ELECTRON-PARAMAGNETIC-RES, LIGHT PHOTOINHIBITION, BINDING-SITE, D1 PROTEIN
in
Biochemistry
volume
35
issue
24
pages
7794 - 7801
publisher
The American Chemical Society
external identifiers
  • scopus:0029973740
ISSN
0006-2960
DOI
10.1021/bi960083p
language
English
LU publication?
yes
id
5b2f032c-cbca-43db-ac56-131b0f847083 (old id 127078)
date added to LUP
2007-08-01 09:26:49
date last changed
2017-01-01 05:09:42
@article{5b2f032c-cbca-43db-ac56-131b0f847083,
  abstract     = {The reaction center protein D1 in photosystem II shows a high turnover during illumination. The degradation of the DI protein is preceded by photoinhibition of the electron transport in photosystem II. There are two distinct mechanisms for this: acceptor-side- and donor-side-induced photoinhibition. Here, donor-side-induced photoinhibition was studied in photosystem II membranes after Cl- depletion or washing with tris(hydroxymethyl)aminomethane (Tris) which destroys water oxidation, reversibly or irreversibly, respectively. Photoinhibition after these treatments leads to fast degradation of the D1 protein, and the mechanism behind this was investigated, Illumination of Cl- depleted photosystem II membranes resulted in a rapid and simultaneous inhibition of Cl--reconstitutable oxygen evolution, loss of 2 Mn ions per photosystem II center, increase in the electron transfer between the electron donor diphenylcarbazide and electron acceptor 2,6-dichlorophenolindophenol, and an increase in the EPR signal IIfast from tyrosine-Z(ox). The destruction of the Mn cluster leads to the loss of oxygen evolution and to an increased accessibility for diphenylcarbazide to donate electrons to Tyr-Z(ox). The increase in the EPR signal from Tyr-Z(ox) can be explained by slower reduction kinetics of Tyr-Z(ox) due to the Mn release. On a longer photoinhibition time scale, a decrease in the amplitude of Tyr-Z(ox) and inhibition of the electron transport from diphenylcarbazide to 2,6-dichlorophenolindophenol occurred simultaneously in both Cl--depleted and Tris-washed photosystem II membranes. These slower photoinhibition reactions were then studied in detail in Tris-washed photosystem II membranes. Compared to photoinhibition of Tyr-Z(ox), the EPR signal from tyrosine-D-ox decreased much slower. Tyr-D-ox was photoinhibited in parallel with the EPRsignals from reduced Q(A), reduced pheophytin, and an oxidized chlorophyll radical (chlorophyll(Z)), This shows that the acceptor side components and the primary charge separation reaction (P680(+) pheophytin(-)) were operational although Tyr-Z was inactivated. The amount of the D1 protein also declined in parallel with Tyr-D-ox, which shows that the D1 protein is not damaged until long after the Mn complex and Tyr-Z have become inactivated. Instead, it is likely that the strongly oxidizing P680(+) is responsible for the damage to the D1 protein.},
  author       = {Jegerschold, C and Styring, Stenbjörn},
  issn         = {0006-2960},
  keyword      = {ACCEPTOR SIDE,OXIDIZING SIDE,RESONANCE SIGNAL-II,REACTION CENTER PROTEIN,SYNECHOCYSTIS SP PCC-6803,SPINACH THYLAKOID MEMBRANES,ELECTRON-PARAMAGNETIC-RES,LIGHT PHOTOINHIBITION,BINDING-SITE,D1 PROTEIN},
  language     = {eng},
  number       = {24},
  pages        = {7794--7801},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {Spectroscopic characterization of intermediate steps involved in donor-side-induced photoinhibition of photosystem II},
  url          = {http://dx.doi.org/10.1021/bi960083p},
  volume       = {35},
  year         = {1996},
}