scholarly journals Structural changes and lateral redistribution of photosystem II during donor side photoinhibition of thylakoids.

1992 ◽  
Vol 119 (2) ◽  
pp. 325-335 ◽  
Author(s):  
R Barbato ◽  
G Friso ◽  
F Rigoni ◽  
F Dalla Vecchia ◽  
G M Giacometti
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Structural Changes ◽  
Protein Complexes ◽  
Gradient Centrifugation ◽  
Photosynthetic Apparatus ◽  
Topological Stability ◽  
Donor Side ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

The structural and topological stability of thylakoid components under photoinhibitory conditions (4,500 microE.m-2.s-1 white light) was studied on Mn depleted thylakoids isolated from spinach leaves. After various exposures to photoinhibitory light, the chlorophyll-protein complexes of both photosystems I and II were separated by sucrose gradient centrifugation and analysed by Western blotting, using a set of polyclonals raised against various apoproteins of the photosynthetic apparatus. A series of events occurring during donor side photoinhibition are described for photosystem II, including: (a) lowering of the oligomerization state of the photosystem II core; (b) cleavage of 32-kD protein D1 at specific sites; (c) dissociation of chlorophyll-protein CP43 from the photosystem II core; and (d) migration of damaged photosystem II components from the grana to the stroma lamellae. A tentative scheme for the succession of these events is illustrated. Some effects of photoinhibition on photosystem I are also reported involving dissociation of antenna chlorophyll-proteins LHCI from the photosystem I reaction center.

scholarly journals Thermal Stress, Aggregation of Chlorophyll-Protein Complexes, and Light-Dependent Recovery of PSII activity in Wheat Seedlings

2021 ◽  
Vol 68 (5) ◽  
pp. 867-872
Author(s):  
M. S. Khristin ◽  
T. N. Smolova ◽  
V. D. Kreslavski
Keyword(s):  
Low Temperature ◽  
Structural Changes ◽  
Protein Complexes ◽  
Red Light ◽  
Photochemical Activity ◽  
Wheat Seedlings ◽  
Psii Activity ◽  
Temperature Spectra ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

Abstract The dynamics of changes in the photochemical activity of photosystem II (PSII) and low-temperature spectra at 77 K in the first leaves of 11-day winter wheat plants Triticum aestivum L., as well as structural changes in chlorophyll-protein complexes (CPC) of thylakoid membranes during recovery after a short-term (20 min) heating at a temperature of 42°C, were studied. Changes in the Fv/Fm, F735/F695, and F735/F685 ratios indicate inhibition of PSII immediately after heating. Using nondenaturing electrophoresis, it was shown that the light-harvesting Chl a/b complex of PSII does not aggregate immediately after heating but after several hours, after 6 h the desagregation of CPC was observed, which was consistent with an increase in the Fv/Fm ratio upon recovery. The influence of temperature, intensity, and quality of light (white, blue, and red light) on the recovery of PSII activity and low-temperature fluorescence spectra was studied. It was concluded that the recovery is a photo-activated low-energy process, independent of photosynthesis, and the most effective in blue light.

scholarly journals Role of the HSP70 Homologue from Chloroplasts in the Assembly of the Photosynthetic Apparatus

1993 ◽  
Author(s):  
Rachel Nechushtai ◽  
Parag Chitnis
Keyword(s):  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Crop Productivity ◽  
Cdna Clones ◽  
Light Harvesting Complex ◽  
Complex Protein ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

The major goal of the proposed research was to study the role of a 70-kDa heat shock cognate protein from chloroplasts (ct-HSP70) in the assembly of chlorophyll-protein complexes. The latters are mostly important in allowing photosynthesis to occur. Photosynthesis is at the heart of crop productivity and the knowledge of the biogenesis of the photosynthetic apparatus is essential to manipulate the efficiency of photosynthesis. The characterization of the function of the ct-HSP70 was planned to be studied in vitro by assaying its capability to physically interact with the thylakoid proteins and to assist their assembly into thylakoid membranes. We planned to identify regions in the light-harvesting complex protein (LHCP) that interact with the ct-HSP70 and characterize the interaction between them. We also intended to isolate cDNA clones encoding ct-HSP70, sequence them, express one of them in E. coli and use the purified protein for functional assays. The research in this BARD proposal aimed at providing insights and aid in understanding the mechanism by which plants may respond to the heat stress. Since plants often experience increased temperatures.

A study of Photosystem II fluorescence emission in terms of the antenna chlorophyll-protein complexes

1993 ◽  
Vol 1183 (1) ◽  
pp. 194-200 ◽  
Author(s):  
Robert C. Jennings ◽  
Flavio M. Garlaschi ◽  
Roberto Bassi ◽  
Giuseppe Zucchelli ◽  
Alberto Vianelli ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Protein Complexes ◽  
Fluorescence Emission ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

scholarly journals Acyl lipids in the supramolecular chlorophyll-protein complexes of photosystems - isolation artifacts or integral components regulating their structure and functions?

2014 ◽  
Vol 57 (3) ◽  
pp. 401-418 ◽  
Author(s):  
Zbigniew Krupa
Keyword(s):  
Photosystem Ii ◽  
Lipid Content ◽  
Protein Complexes ◽  
Thylakoid Membranes ◽  
Supramolecular Complexes ◽  
Hexadecenoic Acid ◽  
Acyl Lipids ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein ◽  
Structure And Functions

The precise nature of interactions between the chloropnyll-protein complexes related to photosystem I or photosystem II and the acyl lipids in the thylakoid membranes is not yet fully elucidated. Analyses of the lipid content of isolated photosystem supramolecular complexes reveal that they are integral components of these complexes. However, the relations between certain acyl lipids and the specific structure and functions of the complexes investigated are still widely discussed. The most generally accepted phenomenon is the fact of participation of phosphatidylglycerol containing the unique <em>trans-</em>Δ<sup>3</sup> -hexadecenoic acid in the oligomerization of the light-harvesting chlorophyll a/b protein complex II.

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