Coupled Activation of the Donor and the Acceptor Side of Photosystem II during Photoactivation of the Oxygen Evolving Cluster†

Biochemistry ◽  
1998 ◽  
Vol 37 (31) ◽  
pp. 11039-11045 ◽  
Author(s):  
Maria Rova ◽  
Fikret Mamedov ◽  
Ann Magnuson ◽  
Per-Olof Fredriksson ◽  
Stenbjörn Styring
Keyword(s):  
Photosystem Ii ◽  
Acceptor Side ◽  
Oxygen Evolving

Coupled Modification of the Acceptor Side of Photosystem II During Photoactivation of the Oxygen Evolving Complex

1998 ◽  
pp. 1471-1474
Author(s):  
M. Royal ◽  
F. Mamedov ◽  
A. Magnuson ◽  
P.-O. Fredriksson ◽  
S. Styring
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolving Complex ◽  
Acceptor Side ◽  
Oxygen Evolving

Quantitative assessment of the high-light tolerance in plants with an impaired photosystem II donor side

2019 ◽  
Vol 476 (9) ◽  
pp. 1377-1386 ◽  
Author(s):  
Sam Wilson ◽  
Alexander V. Ruban
Keyword(s):  
Photosystem Ii ◽  
Redox State ◽  
Photochemical Quenching ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Donor Side ◽  
Acceptor Side ◽  
Oxygen Evolving ◽  
The Impact

Abstract Photoinhibition is the light-induced down-regulation of photosynthetic efficiency, the primary target of which is photosystem II (PSII). Currently, there is no clear consensus on the exact mechanism of this process. However, it is clear that inhibition can occur through limitations on both the acceptor- and donor side of PSII. The former mechanism is caused by electron transport limitations at the PSII acceptor side. Whilst, the latter mechanism relies on the disruption of the oxygen-evolving complex. Both of these mechanisms damage the PSII reaction centre (RC). Using a novel chlorophyll fluorescence methodology, RC photoinactivation can be sensitively measured and quantified alongside photoprotection in vivo. This is achieved through estimation of the redox state of QA, using the parameter of photochemical quenching in the dark (qPd). This study shows that through the use of PSII donor-side inhibitors, such as UV-B and Cd2+, there is a steeper gradient of photoinactivation in the systems with a weakened donor side, independent of the level of NPQ attained. This is coupled with a concomitant decline in the light tolerance of PSII. The native light tolerance is partially restored upon the use of 1,5-diphenylcarbazide (DPC), a PSII electron donor, allowing for the balance between the inhibitory pathways to be sensitively quantified. Thus, this study confirms that the impact of donor-side inhibition can be detected alongside acceptor-side photoinhibition using the qPd parameter and confirms qPd as a valid, sensitive and unambiguous parameter to sensitively quantify the onset of photoinhibition through both acceptor- or donor-side mechanisms.

The Effects of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea on the Photosynthetic Oxygen Complex

1984 ◽  
Vol 39 (5) ◽  
pp. 347-350 ◽  
Author(s):  
Marie-José Delrieu
Keyword(s):  
Photosystem Ii ◽  
Kinetic Properties ◽  
Oxygen Evolving Complex ◽  
Separation Systems ◽  
Acceptor Side ◽  
Oxygen Complex ◽  
Inhibitory Site ◽  
Donor Acceptor ◽  
Photosynthetic Oxygen ◽  
Oxygen Evolving

In the presence of trypsin and ferricyanide as external electron acceptor, lettuce chloroplasts are resistant to DCMU, showing that the inhibitory site of DCMU is only situated on the acceptor side of photosystem II. However, kinetic properties of the oxygen evolving complex are modified at non-saturating concentrations of DCMU. These changes are interpreted in terms of a model with two distinct charges separation systems on the same center: the auxiliary donor- acceptor system DQL implicated in the transitions S1 → S2 and S2 → S3 would be much less affected by DCMU than the main donor-acceptor system YQH after the first flash.

Comparison of susceptibility of leaves on short-term UV-B irradiation

2012 ◽  
Vol 26 (4) ◽  
pp. 395-400
Author(s):  
E. Skórska ◽  
A. Murkowski
Keyword(s):  
Photosystem Ii ◽  
Ultraviolet B ◽  
Oxygen Evolving Complex ◽  
Short Term ◽  
Chlorophyll Fluorescence Parameters ◽  
Acceptor Side ◽  
Donor And Acceptor ◽  
Ultraviolet B Irradiation ◽  
Oxygen Evolving ◽  
Short Time

Abstract The effects of short-time ultraviolet-B irradiation (0.74 kJ m-2 d-1) at light on cucumber and peppermint leaves were studied.Aconsiderable decrease of the most important chlorophyll fluorescence parameters values mainly in the cucumber leaves, compared to the control, was observed. It indicates damages as well as at a donor and acceptor side of photosystem II, specially in the oxygen evolving complex, electron transport and connected with the dark reactions. In the peppermint leaves these values were unchanged or slight decreased. After 24 h from disappearing of the applied UV-B stress, adverse changes became established, especially in the cucumber leaves show irreversible damages of photosystem II. Coefficient of nonphotochemical quenching increased by 50% in the peppermint leaves, while in cucumber remained unchanged. Chlorophyll delayed luminescence coefficient was decreased by 36% in the UV-B irradiated cucumber leaves and by 25% in the peppermint leaves. Content of ultraviolet-absorbing compounds was higher in peppermint leaves by 78% than in the cucumber. Generally, peppermint seemed to be more tolerant to the applied UV-B radiation compared to cucumber.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

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