scholarly journals Structure of photosystem II in spinach thylakoid membranes: comparison of detergent-solubilized and native complexes by electron microscopy

1996 ◽  
Vol 315 (2) ◽  
pp. 543-547 ◽  
Author(s):  
William V. NICHOLSON ◽  
Fiona H. SHEPHERD ◽  
Mark F. ROSENBERG ◽  
Robert C. FORD ◽  
Andreas HOLZENBURG
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Rotational Symmetry ◽  
Thylakoid Membranes ◽  
Two Dimensional ◽  
Rectangular Shape ◽  
Ordered Arrays ◽  
Different Types ◽  
Spinach Thylakoid ◽  
Membrane Bound

1. Electron microscopy of solubilized photosystem II (PSII) complexes and PSII in spinach thylakoid membranes has been carried out and the results have been compared with data obtained from ordered two-dimensional arrays of PSII. Membrane-bound PSII is roughly rectangular (17.6 nm× 14.1 nm) with a central stain cavity surrounded by four major lumenal domains. A comparison between the averaged projections of single (non-ordered) particles at 3.8 nm resolution and the Fourier projection maps obtained from ordered arrays (at 2–3 nm resolution) reveals close similarity and excludes the possibility that PSII observed in two-dimensional ordered arrays represents an unusual subpopulation. 2. After detergent solubilization, PSII adopts various aggregation states which were analysed by electron microscopy in conjunction with single-particle averaging. Two different types of projection of roughly rectangular shape and of dimensions 30 nm×17 nm manifesting themselves as tetrameric sandwich structures have been revealed. This conclusion is supported by the presence of at least two axes of 2-fold rotational symmetry running perpendicular to each other and intersecting at the centre of the oligomer. Comparisons of the structures of detergent-solubilized and native PSII show that the oligomerization of PSII can be artificially induced by the process of membrane solubilization.

scholarly journals Characterization by electron microscopy of isolated particles and two-dimensional crystals of the CP47-D1-D2-cytochrome b-559 complex of photosystem II

Biochemistry ◽  
1990 ◽  
Vol 29 (13) ◽  
pp. 3220-3225 ◽  
Author(s):  
Jan P. Dekker ◽  
Scott D. Betts ◽  
Charles F. Yocum ◽  
Egbert J. Boekema
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Cytochrome B ◽  
Two Dimensional

A highly resolved, oxygen-evolving photosystem II preparation from spinach thylakoid membranes

FEBS Letters ◽  
1981 ◽  
Vol 134 (2) ◽  
pp. 231-234 ◽  
Author(s):  
Deborah A. Berthold ◽  
Gerald T. Babcock ◽  
Charles F. Yocum
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membranes ◽  
Spinach Thylakoid ◽  
Oxygen Evolving

scholarly journals High-Light versus Low-Light: Effects on Paired Photosystem II Supercomplex Structural Rearrangement in Pea Plants

2020 ◽  
Vol 21 (22) ◽  
pp. 8643
Author(s):  
Alessandro Grinzato ◽  
Pascal Albanese ◽  
Roberto Marotta ◽  
Paolo Swuec ◽  
Guido Saracco ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photosystem Ii ◽  
Structural Rearrangement ◽  
Structural Features ◽  
Thylakoid Membranes ◽  
Variable Number ◽  
High Light ◽  
Low Light ◽  
Cryo Electron Microscopy ◽  
Light Effects

In plant grana thylakoid membranes Photosystem II (PSII) associates with a variable number of antenna proteins (LHCII) to form different types of supercomplexes (PSII-LHCII), whose organization is dynamically adjusted in response to light cues, with the C2S2 more abundant in high-light and the C2S2M2 in low-light. Paired PSII-LHCII supercomplexes interacting at their stromal surface from adjacent thylakoid membranes were previously suggested to mediate grana stacking. Here, we present the cryo-electron microscopy maps of paired C2S2 and C2S2M2 supercomplexes isolated from pea plants grown in high-light and low-light, respectively. These maps show a different rotational offset between the two supercomplexes in the pair, responsible for modifying their reciprocal interaction and energetic connectivity. This evidence reveals a different way by which paired PSII-LHCII supercomplexes can mediate grana stacking at diverse irradiances. Electrostatic stromal interactions between LHCII trimers almost completely overlapping in the paired C2S2 can be the main determinant by which PSII-LHCII supercomplexes mediate grana stacking in plants grown in high-light, whereas the mutual interaction of stromal N-terminal loops of two facing Lhcb4 subunits in the paired C2S2M2 can fulfil this task in plants grown in low-light. The high-light induced accumulation of the Lhcb4.3 protein in PSII-LHCII supercomplexes has been previously reported. Our cryo-electron microscopy map at 3.8 Å resolution of the C2S2 supercomplex isolated from plants grown in high-light suggests the presence of the Lhcb4.3 protein revealing peculiar structural features of this high-light-specific antenna important for photoprotection.

Inhibitory Effect of Crown Compound on Photoelectron Transport Activity of Beet Spinach Thylakoid Membranes

1991 ◽  
Vol 46 (1-2) ◽  
pp. 87-92 ◽  
Author(s):  
S. C. Sabat ◽  
V. Vijayavergiya ◽  
B. C. Tripathy ◽  
Prasanna Mohanty
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Thylakoid Membranes ◽  
Dependent Manner ◽  
Transport Activity ◽  
Concentration Dependent Manner ◽  
Variable Yield ◽  
Spinach Thylakoid

Abstract The effect of K-picrate-18-crown-6 (crown) on the photoelectron transport activity of beet spinach thylakoid membranes was investigated. Addition of micromolar concentration of crown to thylakoid preparation inhibited p-benzoquinone, chloride-indophenol, methyl viologen supported Hill activities maximally by 75 per cent in a concentration dependent manner. However, the photosystem I catalyzed reaction remained insensitive to crown suggesting that crown specifically inhibits photosystem II electron transport. Addition of exogenous electron donors like hydroxylamine or diphenylcarbazide failed to restore the crown induced inhibition of photosystem II electron transport and lowering of steady state chlorophyll a fluorescence yield. These observations suggest that crown also inhibits photosystem II catalyzed electron transport after the donation sites of these exogenous donors. Washing of the crown pre-treated thylakoids with isolation buffer, relieved the crown inhibited electron transport activity, indicating that this inhibition is reversible. Furthermore, in hydroxylamine washed thylakoids which are devoid of O2 evolution capacity, the hydroxylamine induced increase in chlorophyll a fluorescence of variable yield was quenched by the addition of crown. These observations suggest that crown affects the oxygen evolution and inhibits at a site close to photosystem II reaction centres.

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