Lipids in and around photosynthetic reaction centres

2005 ◽  
Vol 33 (5) ◽  
pp. 924-930 ◽  
Author(s):  
P.K. Fyfe ◽  
M.R. Jones
Keyword(s):  
Membrane Lipids ◽  
Protein Complexes ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Ps Ii ◽  
X Ray Crystallography ◽  
Structural Support ◽  
Reaction Centres ◽  
Ps I ◽  
Pigment Protein Complexes

Reaction centres are membrane-embedded pigment–protein complexes that transduce the energy of sunlight into a biologically useful form. The most heavily studied reaction centres are the PS-I (Photosystem I) and PS-II complexes from oxygenic phototrophs, and the reaction centre from purple photosynthetic bacteria. A great deal is known about the compositions and structures of these reaction centres, and the mechanism of light-activated transmembrane electron transfer, but less is known about how they interact with other components of the photosynthetic membrane, including the membrane lipids. X-ray crystallography has provided high-resolution structures for PS-I and the purple bacterial reaction centre, and revealed binding sites for a number of lipids, either embedded in the protein interior or attached to the protein surface. These lipids play a variety of roles, including the binding of cofactors and the provision of structural support. The challenges of modelling surface-associated electron density features such as lipids, detergents, small amphiphiles and ions are discussed.

Photosynthetic Responses of Pisum sativum to an Increase in Irradiance During Growth. II. Thylakoid Membrane Components

1987 ◽  
Vol 14 (1) ◽  
pp. 9 ◽  
Author(s):  
WS Chow ◽  
JM Anderson
Keyword(s):  
Thylakoid Membrane ◽  
High Light ◽  
Cytochrome F ◽  
Reaction Centre ◽  
Leaf Photosynthesis ◽  
Low Light ◽  
Ps Ii ◽  
Reaction Centres ◽  
Ps I ◽  
Membrane Components

Following the transfer of pea plants grown at low irradiance (60 �mol photons m-2 s-1, 16 h light/8 h dark cycles) to high irradiance (390 �mol photons m-2 s-1), the extents and time courses of the increase in the concentrations of thylakoid membrane components on a chlorophyll basis have been determined. The increase in cytochrome f (~ 70%) and plastoquinone (~ 50%) contents occurred with no noticeable lag phase. The increase in photosystem Il reaction centres (PS II, ~ 35%) and ATP synthetase (~ 90%) occurred possibly with a lag period of 1-2 days. In contrast, there was no significant increase in the concentration of P700 (reaction centre) of PS I complex. The concentration of PS II reaction centres measured by atrazine-binding exceeded that from the O2 yield per single-turnover flash by a factor of 1.17 (compared with the expected value of 1.14); this contrasts with the factor of 1.8 obtained by P. A. Jursinic and R. Dennenberg [Arch. Biochem. Biophys. (1985) 241, 540-9]. It is suggested that both methods are equivalent for the determination of PS II reaction centres in active chloroplasts. The stoichiometry of PS II : cyt f: PS I was highly flexible, and not fixed at 1 : 1 : 1. We obtained the stoichiometries of 1.25 : 0.7 : 1.0 for low-light pea chloroplasts and 1.7 : 1.25 : 1.0 for chloroplasts in pea plants that had been transferred to high light for about 10 days, demonstrating the dynamic nature of thylakoid composition and function. In the first 2 days after transferring low light pea plants to high light, the time course of the increase in CO2- and light-saturated rate of leaf photosynthesis corresponded better with that of cyt f and plastoquinone than that of other chloroplast components examined. This suggests that, during the transition period, the relatively prompt increase of cyt b/f and plastoquinone plays a part in enhancing the CO2- and light-saturated rate of leaf photosynthesis.

Heat-Induced Alterations in Thylakoid Membrane Protein Composition in Barley

1994 ◽  
Vol 21 (6) ◽  
pp. 759 ◽  
Author(s):  
TS Takeuchi ◽  
JP Thornber
Keyword(s):  
Thylakoid Membrane ◽  
Elevated Temperatures ◽  
Quaternary Structure ◽  
Protein Complexes ◽  
Protein Composition ◽  
Spectroscopic Studies ◽  
Lhc Ii ◽  
Ps Ii ◽  
Ps I ◽  
Pigment Protein Complexes

Biochemical and spectroscopic studies on the effects of high temperatures (45-47� C) over a 1 h period on the protein composition, fluorescence and photochemical activities of the barley thylakoid membrane were made. Photosystem II (PS II) activity decreased as expected, and photosystem I (PS I) activity also unexpectedly decreased. Our data support previous conclusions that the decrease in PS I activity is largely due to inactivation (or loss) of a component between the two photosystems. A two-dimensional electrophoretic system permitted first the separation of the thylakoid pigment-protein complexes of unstressed and stressed plants, followed by a determination of their subunit composition. The changes in the protein composition of each pigment-protein complex in response to elevated temperatures were monitored. Heat changed the quaternary structure of PS II and resulted in removal of the oxygen-evolving enhancer proteins from the thylakoid, but did essentially no damage to the PS I complex. The PS II core complex dissociated from a dimeric form to a monomeric one, and the major LHC II component (LHC IIb) changed from a trimeric to a monomeric form. The pigments that are lost from thylakoids during heat stress are mainly removed from the PS II pigment-proteins.

The Occurrence of β-Carotene-5,6-epoxide in the Photosynthetic Apparatus of Higher Plants

1989 ◽  
Vol 44 (11-12) ◽  
pp. 959-965 ◽  
Author(s):  
Andrew Young ◽  
Paul Barry ◽  
George Britton
Keyword(s):  
Higher Plants ◽  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Reaction Centre ◽  
Higher Plant ◽  
Ps Ii ◽  
Photooxidative Damage ◽  
Pigment Protein Complexes ◽  
The Individual ◽  
Β Carotene

Abstract The occurrence of β-carotene-5,6-epoxide in higher plant photosynthetic tissue is described. The compound is found in isolated chloroplasts, thylakoids and other subchloroplast particles but can only be detected in intact leaves or cotyledons of higher plants when these are exposed to very high light intensities or to inhibitors such as monuron or paraquat. The distribution of the epoxide within the individual pigment-protein complexes is given. It is particularly associated with the PS I reaction centres (C P I and CP la) and less so with the PS II reaction centre (CPa). Circular dichroism shows that the β-carotene-5,6-epoxide isolated from photosynthetic tissue is optically inactive. It is therefore not produced enzymically but is a product of photooxidative events in the photosynthetic apparatus. Its presence in photosynthetic tissue is a reliable indicator of photooxidative damage to the thylakoid membrane involving oxidation of β-carotene.

Photoinactivation of Photosynthetic Electron Transport under Anaerobic and Aerobic Conditions in Isolated Thylakoids of Spinach

1992 ◽  
Vol 47 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Rekha Chaturvedi ◽  
M. Singh ◽  
P. V. Sane
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Ps Ii ◽  
Ps I ◽  
S2 State ◽  
The Stability ◽  
Oxygen Evolving ◽  
Spinach Thylakoids

Abstract The effect of exposure to strong white light on photosynthetic electron transport reactions of PS I and PS II were investigated in spinach thylakoids in the absence or presence of oxygen. Irrespective of the conditions used for photoinactivation, the damage to PS II was always much more than to PS I. Photoinactivation was severe under anaerobic conditions compared to that in air for the same duration. This shows that the presence of oxygen is required for prevention of photoinactivation of thylakoids. The susceptibility of water-splitting complex in photoinactivation is indicated by our data from experiments with chloride-deficient chloroplast membranes wherein it was observed that the whole chain electron transport from DPC to MV was much less photoinhibited than that from water. The data from the photoinactivation experiments with the Tris-treated thylakoids indicate another photodam age site at or near reaction centre of PS II. DCMU-protected PS II and oxygen-evolving complex from photoinactivation. DCMU protection can also be interpreted in terms of the stability of the PS II complex when it is in S2 state.

scholarly journals Pigment-Protein Complexes from the Photosynthetic Membrane of the Cyanobacterium Synechocystis sp. PCC 6803

1995 ◽  
Vol 234 (2) ◽  
pp. 459-465 ◽  
Author(s):  
Roberto Barbato ◽  
Patrizia Polverino Laureto ◽  
Fernanda Rigoni ◽  
Elena Martini ◽  
Giorgio M. Giacometti
Keyword(s):  
Protein Complexes ◽  
Photosynthetic Membrane ◽  
Pigment Protein Complexes ◽  
Synechocystis Sp ◽  
Pcc 6803

Occurrence of Secondary Carotenoids in PS I Complexes Isolated from Eremosphaera viridis De Bary (Chlorophyceae)

1992 ◽  
Vol 47 (1-2) ◽  
pp. 51-56 ◽  
Author(s):  
Burkhard Vechtel ◽  
Elfriede K. Pistorius ◽  
Hans Georg Ruppel
Keyword(s):  
Green Algae ◽  
Photosystem I ◽  
Protein Complexes ◽  
Pigment Composition ◽  
Eremosphaera Viridis ◽  
Ps I ◽  
Pigment Protein Complexes ◽  
Secondary Carotenoids ◽  
Lhc I ◽  
Β Carotene

Abstract Photosystem I complexes of Eremosphaera viridis De Bary (Chlorophyceae, Chlorococcales) were isolated and partially characterized. In the isolated PS I complexes, peptides of 64-60, 26, 23, 20, 15, 11 and 8.5 kDa could be detected. When Eremosphaera was grown under regular conditions the pigment composition of the isolated PS I complexes was similar to that found in PS I complexes from other green algae. However, when Eremosphaera was grown under nitrogen deficient conditions, PS I complexes contained the secondary carotenoids canthaxanthin and traces of astaxanthin and echinenone in addition to β-carotene, violaxanthin and lutein. The results presented indicate that the secondary carotenoids are associated with the LHC I of PS I. To our knowledge this represents the first report about the association of secondary carotenoids with light harvesting pigment protein complexes of green algae.

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