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Sheikh T, Hamid B, Baba Z, Iqbal S, Yatoo A, Fatima S, Nabi A, Kanth R, Dar K, Hussain N, Alturki AI, Sunita K, Sayyed R. Extracellular polymeric substances in psychrophilic cyanobacteria: A potential bioflocculant and carbon sink to mitigate cold stress. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2022. [DOI: 10.1016/j.bcab.2022.102375] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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2
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Santander MV, Schiffer JM, Lee C, Axson JL, Tauber MJ, Prather KA. Factors controlling the transfer of biogenic organic species from seawater to sea spray aerosol. Sci Rep 2022; 12:3580. [PMID: 35246545 PMCID: PMC8897391 DOI: 10.1038/s41598-022-07335-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/27/2022] [Indexed: 11/09/2022] Open
Abstract
Ocean waves transfer sea spray aerosol (SSA) to the atmosphere, and these SSA particles can be enriched in organic matter relative to salts compared to seawater ratios. A fundamental understanding of the factors controlling the transfer of biogenic organic matter from the ocean to the atmosphere remains elusive. Field studies that focus on understanding the connection between organic species in seawater and SSA are complicated by the numerous processes and sources affecting the composition of aerosols in the marine environment. Here, an isolated ocean-atmosphere system enables direct measurements of the sea-air transfer of different classes of biogenic organic matter over the course of two phytoplankton blooms. By measuring excitation-emission matrices of bulk seawater, the sea surface microlayer, and SSA, we investigate time series of the transfer of fluorescent species including chlorophyll-a, protein-like substances, and humic-like substances. Herein, we show the emergence of different molecular classes in SSA at specific times over the course of a phytoplankton bloom, suggesting that SSA chemical composition changes over time in response to changing ocean biological conditions. We compare the temporal behaviors for the transfer of each component, and discuss the factors contributing to differences in transfer between phases.
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Affiliation(s)
- Mitchell V Santander
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA
| | | | - Christopher Lee
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92037, USA
| | | | - Michael J Tauber
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Kimberly A Prather
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093, USA. .,Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92037, USA.
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3
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Role of Microalgae in Global CO2 Sequestration: Physiological Mechanism, Recent Development, Challenges, and Future Prospective. SUSTAINABILITY 2021. [DOI: 10.3390/su132313061] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The rising concentration of global atmospheric carbon dioxide (CO2) has severely affected our planet’s homeostasis. Efforts are being made worldwide to curb carbon dioxide emissions, but there is still no strategy or technology available to date that is widely accepted. Two basic strategies are employed for reducing CO2 emissions, viz. (i) a decrease in fossil fuel use, and increased use of renewable energy sources; and (ii) carbon sequestration by various biological, chemical, or physical methods. This review has explored microalgae’s role in carbon sequestration, the physiological apparatus, with special emphasis on the carbon concentration mechanism (CCM). A CCM is a specialized mechanism of microalgae. In this process, a sub-cellular organelle known as pyrenoid, containing a high concentration of Ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco), helps in the fixation of CO2. One type of carbon concentration mechanism in Chlamydomonas reinhardtii and the association of pyrenoid tubules with thylakoids membrane is represented through a typical graphical model. Various environmental factors influencing carbon sequestration in microalgae and associated techno-economic challenges are analyzed critically.
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Bussi Y, Shimoni E, Weiner A, Kapon R, Charuvi D, Nevo R, Efrati E, Reich Z. Fundamental helical geometry consolidates the plant photosynthetic membrane. Proc Natl Acad Sci U S A 2019; 116:22366-22375. [PMID: 31611387 PMCID: PMC6825288 DOI: 10.1073/pnas.1905994116] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Plant photosynthetic (thylakoid) membranes are organized into complex networks that are differentiated into 2 distinct morphological and functional domains called grana and stroma lamellae. How the 2 domains join to form a continuous lamellar system has been the subject of numerous studies since the mid-1950s. Using different electron tomography techniques, we found that the grana and stroma lamellae are connected by an array of pitch-balanced right- and left-handed helical membrane surfaces of different radii and pitch. Consistent with theoretical predictions, this arrangement is shown to minimize the surface and bending energies of the membranes. Related configurations were proposed to be present in the rough endoplasmic reticulum and in dense nuclear matter phases theorized to exist in neutron star crusts, where the right- and left-handed helical elements differ only in their handedness. Pitch-balanced helical elements of alternating handedness may thus constitute a fundamental geometry for the efficient packing of connected layers or sheets.
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Affiliation(s)
- Yuval Bussi
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Allon Weiner
- Centre d'Immunologie et des Maladies Infectieuses, Cimi-Paris, INSERM, Sorbonne Université, 75013 Paris, France
| | - Ruti Kapon
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dana Charuvi
- Institute of Plant Sciences, Agricultural Research Organization - Volcani Center, 7505101 Rishon LeZion, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Efi Efrati
- Department of Physics of Complex Systems, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ziv Reich
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel;
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5
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Grossmann L, Hinrichs J, Weiss J. Cultivation and downstream processing of microalgae and cyanobacteria to generate protein-based technofunctional food ingredients. Crit Rev Food Sci Nutr 2019; 60:2961-2989. [DOI: 10.1080/10408398.2019.1672137] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Lutz Grossmann
- Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Jörg Hinrichs
- Department of Soft Matter Science and Dairy Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
| | - Jochen Weiss
- Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
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Mareš J, Strunecký O, Bučinská L, Wiedermannová J. Evolutionary Patterns of Thylakoid Architecture in Cyanobacteria. Front Microbiol 2019; 10:277. [PMID: 30853950 PMCID: PMC6395441 DOI: 10.3389/fmicb.2019.00277] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/01/2019] [Indexed: 01/28/2023] Open
Abstract
While photosynthetic processes have become increasingly understood in cyanobacterial model strains, differences in the spatial distribution of thylakoid membranes among various lineages have been largely unexplored. Cyanobacterial cells exhibit an intriguing diversity in thylakoid arrangements, ranging from simple parietal to radial, coiled, parallel, and special types. Although metabolic background of their variability remains unknown, it has been suggested that thylakoid patterns are stable in certain phylogenetic clades. For decades, thylakoid arrangements have been used in cyanobacterial classification as one of the crucial characters for definition of taxa. The last comprehensive study addressing their evolutionary history in cyanobacteria was published 15 years ago. Since then both DNA sequence and electron microscopy data have grown rapidly. In the current study, we map ultrastructural data of >200 strains onto the SSU rRNA gene tree, and the resulting phylogeny is compared to a phylogenomic tree. Changes in thylakoid architecture in general follow the phylogeny of housekeeping loci. Parietal arrangement is resolved as the original thylakoid organization, evolving into complex arrangement in the most derived group of heterocytous cyanobacteria. Cyanobacteria occupying intermediate phylogenetic positions (greater filamentous, coccoid, and baeocytous types) exhibit fascicular, radial, and parallel arrangements, partly tracing the reconstructed course of phylogenetic branching. Contrary to previous studies, taxonomic value of thylakoid morphology seems very limited. Only special cases such as thylakoid absence or the parallel arrangement could be used as taxonomically informative apomorphies. The phylogenetic trees provide evidence of both paraphyly and reversion from more derived architectures in the simple parietal thylakoid pattern. Repeated convergent evolution is suggested for the radial and fascicular architectures. Moreover, thylakoid arrangement is constrained by cell size, excluding the occurrence of complex architectures in cyanobacteria smaller than 2 μm in width. It may further be dependent on unknown (eco)physiological factors as suggested by recurrence of the radial type in unrelated but morphologically similar cyanobacteria, and occurrence of special features throughout the phylogeny. No straightforward phylogenetic congruences have been found between proteins involved in photosynthesis and thylakoid formation, and the thylakoid patterns. Remarkably, several postulated thylakoid biogenesis factors are partly or completely missing in cyanobacteria, challenging their proposed essential roles.
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Affiliation(s)
- Jan Mareš
- Center Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czechia
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Otakar Strunecký
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
- Institute of Aquaculture, Faculty of Fisheries and Protection of Waters, University of South Bohemia, České Budějovice, Czechia
| | - Lenka Bučinská
- Center Algatech, Institute of Microbiology, Czech Academy of Sciences, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Jana Wiedermannová
- Laboratory of Molecular Genetics of Bacteria, Institute of Microbiology, Czech Academy of Sciences, Prague, Czechia
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7
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Thurotte A, Schneider D. The Fusion Activity of IM30 Rings Involves Controlled Unmasking of the Fusogenic Core. FRONTIERS IN PLANT SCIENCE 2019; 10:108. [PMID: 30792728 PMCID: PMC6374351 DOI: 10.3389/fpls.2019.00108] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/23/2019] [Indexed: 05/20/2023]
Abstract
The inner membrane-associated protein of 30 kDa (IM30, also known as Vipp1) is required for thylakoid membrane biogenesis and maintenance in cyanobacteria and chloroplasts. The protein forms large rings of ∼2 MDa and triggers membrane fusion in presence of Mg2+. Based on the here presented observations, IM30 rings are built from dimers of dimers, and formation of these tetrameric building blocks is driven by interactions of the central coiled-coil, formed by helices 2 and 3, and stabilized via additional interactions mainly involving helix 1. Furthermore, helix 1 as well as C-terminal regions of IM30 together negatively regulate ring-ring contacts. We propose that IM30 rings represent the inactive form of IM30, and upon binding to negatively charged membrane surfaces, the here identified fusogenic core of IM30 rings eventually interacts with the lipid bilayer, resulting in membrane destabilization and membrane fusion. Unmasking of the IM30 fusogenic core likely is controlled by Mg2+, which triggers rearrangement of the IM30 ring structure.
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8
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Steiner P, Luckner M, Kerschbaum H, Wanner G, Lütz-Meindl U. Ionic stress induces fusion of mitochondria to 3-D networks: An electron tomography study. J Struct Biol 2018; 204:52-63. [PMID: 29981486 DOI: 10.1016/j.jsb.2018.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/27/2018] [Accepted: 06/30/2018] [Indexed: 01/05/2023]
Abstract
Mitochondria are central organelles for energy supply of cells and play an important role in maintenance of ionic balance. Consequently mitochondria are highly sensitive to any kind of stress to which they mainly response by disturbance of respiration, ROS production and release of cytochrome c into the cytoplasm. Many of the physiological and molecular stress reactions of mitochondria are well known, yet there is a lack of information on corresponding stress induced structural changes. 3-D visualization of high-pressure frozen cells by FIB-SEM tomography and TEM tomography as used for the present investigation provide an excellent tool for studying structure related mitochondrial stress reactions. In the present study it is shown that mitochondria in the unicellular fresh-water algal model system Micrasterias as well as in the closely related aquatic higher plant Lemna fuse to local networks as a consequence of exposure to ionic stress induced by addition of KCl, NaCl and CoCl2. In dependence on concentration and duration of the treatment, fusion of mitochondria occurs either by formation of protuberances arising from the outer mitochondrial membrane, or by direct contact of the surface of elongated mitochondria. As our results show that respiration is maintained in both model systems during ionic stress and mitochondrial fusion, as well as formation of protuberances are reversible, we assume that mitochondrial fusion is a ubiquitous process that may help the cells to cope with stress. This may occur by interconnecting the respiratory chains of the individual mitochondria and by enhancing the buffer capacity against stress induced ionic imbalance.
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Affiliation(s)
- Philip Steiner
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria
| | - Manja Luckner
- Ultrastructural Research, Faculty of Biology, Ludwig-Maximilians-University, Munich, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany
| | - Hubert Kerschbaum
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria
| | - Gerhard Wanner
- Ultrastructural Research, Faculty of Biology, Ludwig-Maximilians-University, Munich, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany
| | - Ursula Lütz-Meindl
- Department of Biosciences, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria.
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9
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Jilly R, Khan NZ, Aronsson H, Schneider D. Dynamin-Like Proteins Are Potentially Involved in Membrane Dynamics within Chloroplasts and Cyanobacteria. FRONTIERS IN PLANT SCIENCE 2018; 9:206. [PMID: 29520287 PMCID: PMC5827413 DOI: 10.3389/fpls.2018.00206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 02/02/2018] [Indexed: 05/24/2023]
Abstract
Dynamin-like proteins (DLPs) are a family of membrane-active proteins with low sequence identity. The proteins operate in different organelles in eukaryotic cells, where they trigger vesicle formation, membrane fusion, or organelle division. As discussed here, representatives of this protein family have also been identified in chloroplasts and DLPs are very common in cyanobacteria. Since cyanobacteria and chloroplasts, an organelle of bacterial origin, have similar internal membrane systems, we suggest that DLPs are involved in membrane dynamics in cyanobacteria and chloroplasts. Here, we discuss the features and activities of DLPs with a focus on their potential presence and activity in chloroplasts and cyanobacteria.
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Affiliation(s)
- Ruven Jilly
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Nadir Zaman Khan
- Department of Biotechnology, University of Malakand, Malakand, Pakistan
| | - Henrik Aronsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Dirk Schneider
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
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10
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Heureux AMC, Young JN, Whitney SM, Eason-Hubbard MR, Lee RBY, Sharwood RE, Rickaby REM. The role of Rubisco kinetics and pyrenoid morphology in shaping the CCM of haptophyte microalgae. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3959-3969. [PMID: 28582571 PMCID: PMC5853415 DOI: 10.1093/jxb/erx179] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 05/15/2017] [Indexed: 05/18/2023]
Abstract
The haptophyte algae are a cosmopolitan group of primary producers that contribute significantly to the marine carbon cycle and play a major role in paleo-climate studies. Despite their global importance, little is known about carbon assimilation in haptophytes, in particular the kinetics of their Form 1D CO2-fixing enzyme, Rubisco. Here we examine Rubisco properties of three haptophytes with a range of pyrenoid morphologies (Pleurochrysis carterae, Tisochrysis lutea, and Pavlova lutheri) and the diatom Phaeodactylum tricornutum that exhibit contrasting sensitivities to the trade-offs between substrate affinity (Km) and turnover rate (kcat) for both CO2 and O2. The pyrenoid-containing T. lutea and P. carterae showed lower Rubisco content and carboxylation properties (KC and kCcat) comparable with those of Form 1D-containing non-green algae. In contrast, the pyrenoid-lacking P. lutheri produced Rubisco in 3-fold higher amounts, and displayed a Form 1B Rubisco kCcat-KC relationship and increased CO2/O2 specificity that, when modeled in the context of a C3 leaf, supported equivalent rates of photosynthesis to higher plant Rubisco. Correlation between the differing Rubisco properties and the occurrence and localization of pyrenoids with differing intracellular CO2:O2 microenvironments has probably influenced the divergent evolution of Form 1B and 1D Rubisco kinetics.
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Affiliation(s)
- Ana M C Heureux
- University of Oxford, Department of Earth Sciences, South Parks Road, Oxford, UK
| | - Jodi N Young
- University of Washington, School of Oceanography, Seattle, WA, USA
| | - Spencer M Whitney
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT, Australia
| | | | - Renee B Y Lee
- University of Oxford, Department of Earth Sciences, South Parks Road, Oxford, UK
- University of Reading, School of Biological Sciences, Reading, Berkshire, UK
| | - Robert E Sharwood
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Rosalind E M Rickaby
- University of Oxford, Department of Earth Sciences, South Parks Road, Oxford, UK
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Heidrich J, Thurotte A, Schneider D. Specific interaction of IM30/Vipp1 with cyanobacterial and chloroplast membranes results in membrane remodeling and eventually in membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:537-549. [PMID: 27693914 DOI: 10.1016/j.bbamem.2016.09.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/19/2016] [Accepted: 09/21/2016] [Indexed: 12/22/2022]
Abstract
The photosynthetic light reaction takes place within the thylakoid membrane system in cyanobacteria and chloroplasts. Besides its global importance, the biogenesis, maintenance and dynamics of this membrane system are still a mystery. In the last two decades, strong evidence supported the idea that these processes involve IM30, the inner membrane-associated protein of 30kDa, a protein also known as the vesicle-inducing protein in plastids 1 (Vipp1). Even though we just only begin to understand the precise physiological function of this protein, it is clear that interaction of IM30 with membranes is crucial for biogenesis of thylakoid membranes. Here we summarize and discuss forces guiding IM30-membrane interactions, as the membrane properties as well as the oligomeric state of IM30 appear to affect proper interaction of IM30 with membrane surfaces. Interaction of IM30 with membranes results in an altered membrane structure and can finally trigger fusion of adjacent membranes, when Mg2+ is present. Based on recent results, we finally present a model summarizing individual steps involved in IM30-mediated membrane fusion. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Jennifer Heidrich
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Adrien Thurotte
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Dirk Schneider
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
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12
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Cyanobacterial Alkanes Modulate Photosynthetic Cyclic Electron Flow to Assist Growth under Cold Stress. Sci Rep 2015; 5:14894. [PMID: 26459862 PMCID: PMC4602277 DOI: 10.1038/srep14894] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/11/2015] [Indexed: 12/20/2022] Open
Abstract
All cyanobacterial membranes contain diesel-range C15-C19 hydrocarbons at concentrations similar to chlorophyll. Recently, two universal but mutually exclusive hydrocarbon production pathways in cyanobacteria were discovered. We engineered a mutant of Synechocystis sp. PCC 6803 that produces no alkanes, which grew poorly at low temperatures. We analyzed this defect by assessing the redox kinetics of PSI. The mutant exhibited enhanced cyclic electron flow (CEF), especially at low temperature. CEF raises the ATP:NADPH ratio from photosynthesis and balances reductant requirements of biosynthesis with maintaining the redox poise of the electron transport chain. We conducted in silico flux balance analysis and showed that growth rate reaches a distinct maximum for an intermediate value of CEF equivalent to recycling 1 electron in 4 from PSI to the plastoquinone pool. Based on this analysis, we conclude that the lack of membrane alkanes causes higher CEF, perhaps for maintenance of redox poise. In turn, increased CEF reduces growth by forcing the cell to use less energy-efficient pathways, lowering the quantum efficiency of photosynthesis. This study highlights the unique and universal role of medium-chain hydrocarbons in cyanobacterial thylakoid membranes: they regulate redox balance and reductant partitioning in these oxygenic photosynthetic cells under stress.
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13
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Engel BD, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM, Baumeister W. Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography. eLife 2015; 4. [PMID: 25584625 PMCID: PMC4292175 DOI: 10.7554/elife.04889] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/08/2014] [Indexed: 12/19/2022] Open
Abstract
Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ∼15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix. DOI:http://dx.doi.org/10.7554/eLife.04889.001 Many organisms can harvest light to produce their own energy through a process called photosynthesis. In plant and algal cells, photosynthesis takes place within the chloroplasts, which are compartments that contain stacks of structures called thylakoids. Inside the thylakoids, proteins absorb energy from light and convert it into biochemical energy that can be used by the cell. This energy then powers a series of reactions that result in carbon dioxide being incorporated into energy-rich sugars. The enzyme RuBisCO is essential for this process, and is believed to be the most abundant protein on Earth. In land plants, RuBisCO is found throughout the chloroplast, but in algae it is limited to a specialized area called the pyrenoid. Much of our current knowledge of chloroplast structure comes from transmission electron microscopy (TEM) images. However, the traditional methods used to prepare cells for TEM can damage their internal structures. Also, previous studies have focused primarily on the chloroplasts of land plants, even though aquatic organisms—including the alga Chlamydomonas—account for over 50% of photosynthesis on the planet. Here, Engel et al. provide the first three-dimensional structures of Chlamydomonas chloroplasts in their natural state. They used several recently-developed techniques to study cells that were preserved in a close-to-living condition. The cells were rapidly frozen, thinned with a technique called cryo-focused ion beam milling, and then imaged by a type of TEM called cryo-electron tomography. The three-dimensional images provide many insights into the Chlamydomonas chloroplast, including evidence that lipids and proteins move between the membrane that surrounds the chloroplast—called the chloroplast envelope—and the tips of the thylakoids. These images show how thylakoids may be built by the transport of molecules from the chloroplast envelope. In addition, the images reveal the detailed structures of the tubes that connect the thylakoids to the pyrenoid, which could explain how the two stages of photosynthesis (light harvesting and the conversion of carbon dioxide) can be coordinated even though they occur at different places within the chloroplast. Engel et al. also observed that RuBisCO enzymes are arranged in a hexagonal pattern inside the pyrenoid, but are spaced too far apart to make direct contact with each other. To understand how the pyrenoid is assembled, a future goal will be to determine what causes RuBisCO to be arranged in this way. DOI:http://dx.doi.org/10.7554/eLife.04889.002
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Affiliation(s)
- Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Luis Kuhn Cuellar
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elizabeth Villa
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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14
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Engel BD, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM, Baumeister W. Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography. eLife 2015. [PMID: 25584625 DOI: 10.7554/elife.04889#sthash.yy91intr.dpuf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ~15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix.
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Affiliation(s)
- Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Luis Kuhn Cuellar
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elizabeth Villa
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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Alterations in Structural Organization Affect the Functional Ability of Photosynthetic Apparatus. ACTA ACUST UNITED AC 2014. [DOI: 10.1201/b16675-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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