Structure, Composition, Functional Organization and Dynamic Properties of Thylakoid Membranes

Staehelin, L. Andrew; Staay, G.W.M. van der

doi:10.1007/0-306-48127-8_2

Cited by 72 publications

(70 citation statements)

References 87 publications

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“…Finally, quantification of the cyt b 6 f content in stroma lamellae revealed almost no change (Fig. 2), consistent with data showing a homogenous distribution of this complex between stacked and unstacked thylakoids (14,15).…”

Section: Resultssupporting

confidence: 86%

“…In contrast to BBY membranes, the grana membranes isolated by digitonin treatment still contained the cyt b 6 f complex. From difference spectroscopic measurements of cyt f and cyt b 6, we determined a chlorophyll/cyt b 6 f complex ratio of 1,362 ± 73 (n = 5), indicating a more native membrane state compared with BBY membranes (14)(15)(16). FRAP data are summarized in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Knowledge of protein diffusion in unstacked thylakoid regions is limited to grana end membranes (45) and the exchange between granaseparated stroma lamellae (46). Protein mobility is expected to be higher in stroma lamellae than in grana thylakoids, because of a lower protein-packing density (15,47). The protein-packing density in stroma lamellae is significant, however.…”

Section: Discussionmentioning

confidence: 99%

“…This structural heterogeneity is accompanied by, and partly driven by, differential protein distributions. PSII and LHCII are concentrated in grana stacks, photosystem I (PSI) and the ATPase are more abundant in stroma lamellae, whereas the cytochrome (cyt) b 6 f complex is assumed to be distributed homogenously (14)(15)(16)). …”

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confidence: 99%

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Architectural switch in plant photosynthetic membranes induced by light stress

Herbstová

Tietz

Kinzel

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

143

113

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Unavoidable side reactions of photosynthetic energy conversion can damage the water-splitting photosystem II (PSII) holocomplex embedded in the thylakoid membrane system inside chloroplasts. Plant survival is crucially dependent on an efficient molecular repair of damaged PSII realized by a multistep repair cycle. The PSII repair cycle requires a brisk lateral protein traffic between stacked grana thylakoids and unstacked stroma lamellae that is challenged by the tight stacking and low protein mobility in grana. We demonstrated that high light stress induced two main structural changes that work synergistically to improve the accessibility between damaged PSII in grana and its repair machinery in stroma lamellae: lateral shrinkage of grana diameter and increased protein mobility in grana thylakoids. It follows that high light stress triggers an architectural switch of the thylakoid network that is advantageous for swift protein repair. Studies of the thylakoid kinase mutant stn8 and the double mutant stn7/8 demonstrate the central role of protein phosphorylation for the structural alterations. These findings are based on the elaboration of mathematical tools for analyzing confocal laser-scanning microscopic images to study changes in the sophisticated thylakoid architecture in intact protoplasts.confocal microscopy | macromolecular crowding | photosynthesis P hotosynthetic transformation of sunlight into metabolic energy equivalents is a dangerous venture, because toxic side products of the primary photochemical processes can lead to uncontrolled damage. Harmful photosynthetic side reactions cannot be avoided completely and become a serious problem under stress (e.g., high light stress). The main target of photoinhibition (PI) is the D1 subunit of the water-splitting photosystem II (PSII) (1, 2). The D1 subunit is buried in the massive (1,400 kDa) PSII holocomplex that is organized as a dimer and binds between two and four trimeric light-harvesting complex IIs (LHCIIs) (3, 4). Estimates predict that without repair of damaged PSII, the efficiency for photosynthetic energy conversion would drop below 5% (5). Consequently, plants would not survive in a highly dynamic and competitive natural environment. Plants address this challenge through the evolutionary invention of one of the fastest and most efficient molecular repair mechanisms in nature, the PSII repair cycle (5-7).The PSII repair cycle consist of a series of events, including phosphorylation/ dephosphorylation of PSII subunits, holocomplex disassembly/reassembly, and D1 degradation/de novo synthesis (8-10). All of these reactions are harbored in or at the thylakoid membrane system inside the chloroplast. The complex folding of the thylakoid membrane leads to a structural differentiation into stacked grana regions interconnected by unstacked stroma lamellae (11)(12)(13). This structural heterogeneity is accompanied by, and partly driven by, differential protein distributions. PSII and LHCII are concentrated in grana stacks, photosystem I (PSI) and the ATPas...

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Architectural switch in plant photosynthetic membranes induced by light stress

Herbstová

Tietz

Kinzel

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

143

113

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“…Membrane integral protein complexes (PSII, LHCII) protrude as little knobs out of the monolayer plane (see figure). It is well established 39 that the larger particles represent PSII (see, i.e., the EF face of the unfused BBY membrane) whereas the smaller protrusions represent LHCII (see, i.e., the PF face of the unfused BBY membrane). Note the significantly lower particle density after fusion with lipid liposomes (lower panel) compared to unfused BBY membranes (upper panel), indicating dilution of the protein density.…”

Section: ■ Resultsmentioning

confidence: 99%

Carotenoid–Chlorophyll Coupling and Fluorescence Quenching Correlate with Protein Packing Density in Grana-Thylakoids

et al. 2013

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ABSTRACT:The regulation of light-harvesting in photosynthesis under conditions of varying solar light irradiation is essential for the survival and fitness of plants and algae. It has been proposed that rearrangements of protein distribution in the stacked grana region of thylakoid membranes connected to changes in the electronic pigment-interaction play a key role for this regulation. In particular, carotenoid−chlorophyll interactions seem to be crucial for the downregulation of photosynthetic light-harvesting. So far, it has been difficult to determine the influence of the dense protein packing found in native photosynthetic membrane on these interactions. We investigated the changes of the electronic couplings between carotenoids and chlorophylls and the quenching in grana thylakoids of varying protein packing density by two-photon spectroscopy, conventional chlorophyll fluorometry, low-temperature fluorescence spectroscopy, and electron micrographs of freeze-fracture membranes. We observed an increasing carotenoid−chlorophyll coupling and fluorescence quenching with increasing packing density. Simultaneously, the antennas size and excitonic connectivity of Photosystem II increased with increasing quenching and carotenoid−chlorophyll coupling whereas isolated, decoupled LHCII trimers decreased. Two distinct quenching data regimes could be identified that show up at different protein packing densities. In the regime corresponding to higher protein packing densities, quenching is strongly correlated to carotenoid−chlorophyll interactions whereas in the second regime, a weak correlation is apparent with low protein packing densities. Native membranes are in the strong-coupling data regime. Consequently, PSII and LHCII in grana membranes of plants are already quenched by protein crowding. We concluded that this ensures efficient electronic connection of all pigment−protein complexes for intermolecular energy transfer to the reaction centers and allows simultaneously sensitive regulation of light harvesting by only small changes in the protein packaging. ■ INTRODUCTIONPhotosynthesis in higher plants and algae is initiated by the harvesting of sunlight through a series of pigment−protein complexes located in the thylakoid membranes of chloroplasts. Starting from these light harvesting complexes (LHCs), the absorbed energy is efficiently transferred from one complex to the other. These transfer processes end up in the photosystem reaction centers where the energy is converted into redox energy. However, plants are exposed to changing light intensities on a daily basis that can vary over several orders of magnitude. 1 Thus, a regulation mechanism is necessary that assures effective usage of sunlight energy under low-light conditions but avoids photo-oxidative damage to the reaction centers or other parts of the photosynthetic apparatus if the absorbed light exceeds its capacity. A main mechanism that evolved to minimize photo-oxidative damage in plants is called high-energy quenching (qE). qE enables the dissipation ...

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Electron Transfer Pathways and Components

Blankenship

2002

Molecular Mechanisms of Photosynthesis

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Structure, Composition, Functional Organization and Dynamic Properties of Thylakoid Membranes

Cited by 72 publications

References 87 publications

Architectural switch in plant photosynthetic membranes induced by light stress

Architectural switch in plant photosynthetic membranes induced by light stress

Carotenoid–Chlorophyll Coupling and Fluorescence Quenching Correlate with Protein Packing Density in Grana-Thylakoids

Electron Transfer Pathways and Components

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