scholarly journals Structural and functional analyses of photosystem II in the marine diatom Phaeodactylum tricornutum

2019 ◽  
Vol 116 (35) ◽  
pp. 17316-17322 ◽  
Author(s):  
Orly Levitan ◽  
Muyuan Chen ◽  
Xuyuan Kuang ◽  
Kuan Yu Cheong ◽  
Jennifer Jiang ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Spatial Organization ◽  
Higher Plants ◽  
Electron Tomography ◽  
Protein Complexes ◽  
Spatial Differentiation ◽  
Thylakoid Membranes ◽  
Marine Diatom ◽  
Red Algal ◽  
Antenna Proteins

A descendant of the red algal lineage, diatoms are unicellular eukaryotic algae characterized by thylakoid membranes that lack the spatial differentiation of stroma and grana stacks found in green algae and higher plants. While the photophysiology of diatoms has been studied extensively, very little is known about the spatial organization of the multimeric photosynthetic protein complexes within their thylakoid membranes. Here, using cryo-electron tomography, proteomics, and biophysical analyses, we elucidate the macromolecular composition, architecture, and spatial distribution of photosystem II complexes in diatom thylakoid membranes. Structural analyses reveal 2 distinct photosystem II populations: loose clusters of complexes associated with antenna proteins and compact 2D crystalline arrays of dimeric cores. Biophysical measurements reveal only 1 photosystem II functional absorption cross section, suggesting that only the former population is photosynthetically active. The tomographic data indicate that the arrays of photosystem II cores are physically separated from those associated with antenna proteins. We hypothesize that the islands of photosystem cores are repair stations, where photodamaged proteins can be replaced. Our results strongly imply convergent evolution between the red and the green photosynthetic lineages toward spatial segregation of dynamic, functional microdomains of photosystem II supercomplexes.

scholarly journals Probing the biogenesis pathway and dynamics of thylakoid membranes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tuomas Huokko ◽  
Tao Ni ◽  
Gregory F. Dykes ◽  
Deborah M. Simpson ◽  
Philip Brownridge ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Photosystem I ◽  
Spatial Organization ◽  
Electron Flux ◽  
Protein Complexes ◽  
Thylakoid Membranes ◽  
Thylakoid Biogenesis ◽  
Photosynthetic Complexes ◽  
Photosynthetic Machinery ◽  
Pcc 7942

AbstractHow thylakoid membranes are generated to form a metabolically active membrane network and how thylakoid membranes orchestrate the insertion and localization of protein complexes for efficient electron flux remain elusive. Here, we develop a method to modulate thylakoid biogenesis in the rod-shaped cyanobacterium Synechococcus elongatus PCC 7942 by modulating light intensity during cell growth, and probe the spatial-temporal stepwise biogenesis process of thylakoid membranes in cells. Our results reveal that the plasma membrane and regularly arranged concentric thylakoid layers have no physical connections. The newly synthesized thylakoid membrane fragments emerge between the plasma membrane and pre-existing thylakoids. Photosystem I monomers appear in the thylakoid membranes earlier than other mature photosystem assemblies, followed by generation of Photosystem I trimers and Photosystem II complexes. Redistribution of photosynthetic complexes during thylakoid biogenesis ensures establishment of the spatial organization of the functional thylakoid network. This study provides insights into the dynamic biogenesis process and maturation of the functional photosynthetic machinery.

Role of cryo-ET in membrane bioenergetics research

2013 ◽  
Vol 41 (5) ◽  
pp. 1227-1234 ◽  
Author(s):  
Karen M. Davies ◽  
Bertram Daum
Keyword(s):  
Spatial Organization ◽  
Electron Tomography ◽  
Protein Complexes ◽  
Mitochondrial Diseases ◽  
Atp Synthesis ◽  
Cellular Level ◽  
Molecular Organization ◽  
Cellular Context ◽  
Membrane Bound ◽  
The Individual

To truly understand bioenergetic processes such as ATP synthesis, membrane-bound substrate transport or flagellar rotation, systems need to be analysed in a cellular context. Cryo-ET (cryo-electron tomography) is an essential part of this process, as it is currently the only technique which can directly determine the spatial organization of proteins at the level of both the cell and the individual protein complexes. The need to assess bioenergetic processes at a cellular level is becoming more and more apparent with the increasing interest in mitochondrial diseases. In recent years, cryo-ET has contributed significantly to our understanding of the molecular organization of mitochondria and chloroplasts. The present mini-review first describes the technique of cryo-ET and then discusses its role in membrane bioenergetics specifically in chloroplasts and mitochondrial research.

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.

scholarly journals Proteomic Insights into Phycobilisome Degradation, A Selective and Tightly Controlled Process in The Fast-Growing Cyanobacterium Synechococcus elongatus UTEX 2973

Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 374 ◽  
Author(s):  
Aparna Nagarajan ◽  
Mowei Zhou ◽  
Amelia Y. Nguyen ◽  
Michelle Liberton ◽  
Komal Kedia ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Photosystem Ii ◽  
Doubling Time ◽  
Protein Complexes ◽  
Thylakoid Membranes ◽  
Synechococcus Elongatus ◽  
Nutrient Depletion ◽  
Reversible Process ◽  
Fast Growing ◽  
Pigment Protein Complexes

Phycobilisomes (PBSs) are large (3–5 megadalton) pigment-protein complexes in cyanobacteria that associate with thylakoid membranes and harvest light primarily for photosystem II. PBSs consist of highly ordered assemblies of pigmented phycobiliproteins (PBPs) and linker proteins that can account for up to half of the soluble protein in cells. Cyanobacteria adjust to changing environmental conditions by modulating PBS size and number. In response to nutrient depletion such as nitrogen (N) deprivation, PBSs are degraded in an extensive, tightly controlled, and reversible process. In Synechococcus elongatus UTEX 2973, a fast-growing cyanobacterium with a doubling time of two hours, the process of PBS degradation is very rapid, with 80% of PBSs per cell degraded in six hours under optimal light and CO2 conditions. Proteomic analysis during PBS degradation and re-synthesis revealed multiple proteoforms of PBPs with partially degraded phycocyanobilin (PCB) pigments. NblA, a small proteolysis adaptor essential for PBS degradation, was characterized and validated with targeted mass spectrometry. NblA levels rose from essentially 0 to 25,000 copies per cell within 30 min of N depletion, and correlated with the rate of decrease in phycocyanin (PC). Implications of this correlation on the overall mechanism of PBS degradation during N deprivation are discussed.

Isolation and Characterization of Photosystem II of Porphyra yezoensis Ueda

2004 ◽  
Vol 36 (11) ◽  
pp. 780-785 ◽  
Author(s):  
Zheng-Quan Gao ◽  
Guang-Ce Wang ◽  
Cheng-Kui Tseng
Keyword(s):  
Photosystem Ii ◽  
Higher Plants ◽  
Porphyra Yezoensis ◽  
Sucrose Density Gradient ◽  
Thylakoid Membranes ◽  
Isolation And Characterization ◽  
Sds Page ◽  
Cyt C ◽  
First Time

Abstract The thylakoid membranes were isolated and purified from gametophyte of Porphyra yezoensis Ueda (P. yezoensis) by sucrose density gradient ultracentrifugation. After P. yezoensis gametophyte thylakoid membranes were solubilized with SDS, the photosystem II (PSII) particles were isolated and purified. The activity of PSII particles was determined with DCIP (2,6-dichloroindophenol) photoreduction reaction. The composition of purified PSII particles was detected by SDS-PAGE. As a result, seven proteins including 55 kD protein, 47 kD protein, 43 kD protein, 33 kD protein, 31 kD protein, 29 kD protein, and 18 kD protein were found. Compared with PSII particles of higher plants and other algae, they were identified as D1/D2 complex, CP47, CP43, 33 kD protein, D1, D2 and cyt c-550 respectively. Besides, other three new proteins of 20 kD, 16 kD and 14 kD respectively were found. Among these extrinsic proteins, the 16 kD and 14 kD proteins had not been reported previously, and the 20 kD protein was found for the first time in multicellular red algae.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent for the integrity of membrane protein complexes. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of Photosystem II photoactivation.

scholarly journals Charting the native architecture of Chlamydomonas thylakoid membranes with single-molecule precision

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Wojciech Wietrzynski ◽  
Miroslava Schaffer ◽  
Dimitry Tegunov ◽  
Sahradha Albert ◽  
Atsuko Kanazawa ◽  
...  
Keyword(s):  
Single Molecule ◽  
Electron Tomography ◽  
Protein Complexes ◽  
Membrane Surface ◽  
Thylakoid Membranes ◽  
Surface Topology ◽  
Thylakoid Stacking ◽  
Molecular Forces ◽  
Photosynthetic Regulation ◽  
The Individual

Thylakoid membranes scaffold an assortment of large protein complexes that work together to harness the energy of light. It has been a longstanding challenge to visualize how the intricate thylakoid network organizes these protein complexes to finely tune the photosynthetic reactions. Previously, we used in situ cryo-electron tomography to reveal the native architecture of thylakoid membranes (Engel et al., 2015). Here, we leverage technical advances to resolve the individual protein complexes within these membranes. Combined with a new method to visualize membrane surface topology, we map the molecular landscapes of thylakoid membranes inside green algae cells. Our tomograms provide insights into the molecular forces that drive thylakoid stacking and reveal that photosystems I and II are strictly segregated at the borders between appressed and non-appressed membrane domains. This new approach to charting thylakoid topology lays the foundation for dissecting photosynthetic regulation at the level of single protein complexes within the cell.

scholarly journals Pre-purification of diatom pigment protein complexes provides insight into the heterogeneity of FCP complexes

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Marcel Kansy ◽  
Daniela Volke ◽  
Line Sturm ◽  
Christian Wilhelm ◽  
Ralf Hoffmann ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Higher Plants ◽  
Protein Complexes ◽  
Photosynthetic Apparatus ◽  
Thalassiosira Pseudonana ◽  
Photochemical Quenching ◽  
Complex Nature ◽  
Published Data ◽  
Core Complex ◽  
Pigment Protein Complexes

Abstract Background Although our knowledge about diatom photosynthesis has made huge progress over the last years, many aspects about their photosynthetic apparatus are still enigmatic. According to published data, the spatial organization as well as the biochemical composition of diatom thylakoid membranes is significantly different from that of higher plants. Results In this study the pigment protein complexes of the diatom Thalassiosira pseudonana were isolated by anion exchange chromatography. A step gradient was used for the elution process, yielding five well-separated pigment protein fractions which were characterized in detail. The isolation of photosystem (PS) core complex fractions, which contained fucoxanthin chlorophyll proteins (FCPs), enabled the differentiation between different FCP complexes: FCP complexes which were more closely associated with the PSI and PSII core complexes and FCP complexes which built-up the peripheral antenna. Analysis by mass spectrometry showed that the FCP complexes associated with the PSI and PSII core complexes contained various Lhcf proteins, including Lhcf1, Lhcf2, Lhcf4, Lhcf5, Lhcf6, Lhcf8 and Lhcf9 proteins, while the peripheral FCP complexes were exclusively composed of Lhcf8 and Lhcf9. Lhcr proteins, namely Lhcr1, Lhcr3 and Lhcr14, were identified in fractions containing subunits of the PSI core complex. Lhcx1, Lhcx2 and Lhcx5 proteins co-eluted with PSII protein subunits. The first fraction contained an additional Lhcx protein, Lhcx6_1, and was furthermore characterized by high concentrations of photoprotective xanthophyll cycle pigments. Conclusion The results of the present study corroborate existing data, like the observation of a PSI-specific antenna complex in diatoms composed of Lhcr proteins. They complement other data, like e.g. on the protein composition of the 21 kDa FCP band or the Lhcf composition of FCPa and FCPb complexes. They also provide interesting new information, like the presence of the enzyme diadinoxanthin de-epoxidase in the Lhcx-containing PSII fraction, which might be relevant for the process of non-photochemical quenching. Finally, the high negative charge of the main FCP fraction may play a role in the organization and structure of the native diatom thylakoid membrane. Thus, the results present an important contribution to our understanding of the complex nature of the diatom antenna system.

scholarly journals High-resolution model of Arabidopsis Photosystem II reveals the structural consequences of digitonin-extraction

2021 ◽  
Author(s):  
André T. Graça ◽  
Michael Hall ◽  
Karina Persson ◽  
Wolfgang P. Schröder
Keyword(s):  
High Resolution ◽  
Photosystem Ii ◽  
Metal Ion ◽  
Higher Plants ◽  
Protein Complexes ◽  
Early Stage ◽  
Model Organism ◽  
Higher Plant ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractIn higher plants, the photosynthetic process is performed and regulated by Photosystem II (PSII). Arabidopsis thaliana was the first higher plant with a fully sequenced genome, conferring it the status of a model organism; nonetheless, a high-resolution structure of its Photosystem II is missing. We present the first Cryo-EM high-resolution structure of Arabidopsis PSII supercomplex with average resolution of 2.79 Å, an important model for future PSII studies. The digitonin extracted PSII complexes demonstrate the importance of: the LHG2630-lipid-headgroup in the trimerization of the light-harvesting complex II; the stabilization of the PsbJ subunit and the CP43-loop E by DGD520-lipid; the choice of detergent to maintain the integrity of membrane protein complexes. We propose that PsbW and PsbH subunits participate in the phospho-signalling dimerization of the complex, important to the assembly/repair processes of Photosystem II. Furthermore, our data shows at the anticipated Mn4CaO5-site a single metal ion density as a reminiscent early stage of PSII photoactivation.

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