Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Year
  • 1
    Language: English
    In: Plant physiology, August 2014, Vol.165(4), pp.1604-1617
    Description: To investigate the functional importance of Proton Gradient Regulation5-Like1 (PGRL1) for photosynthetic performances in the moss Physcomitrella patens, we generated a pgrl1 knockout mutant. Functional analysis revealed diminished nonphotochemical quenching (NPQ) as well as decreased capacity for cyclic electron flow (CEF) in pgrl1. Under anoxia, where CEF is induced, quantitative proteomics evidenced severe down-regulation of photosystems but up-regulation of the chloroplast NADH dehydrogenase complex, plastocyanin, and Ca sensors in the mutant, indicating that the absence of PGRL1 triggered a mechanism compensatory for diminished CEF. On the other hand, proteins required for NPQ, such as light-harvesting complex stress-related protein1 (LHCSR1), violaxanthin de-epoxidase, and PSII subunit S, remained stable. To further investigate the interrelation between CEF and NPQ, we generated a pgrl1 npq4 double mutant in the green alga Chlamydomonas reinhardtii lacking both PGRL1 and LHCSR3 expression. Phenotypic comparative analyses of this double mutant, together with the single knockout strains and with the P. patens pgrl1, demonstrated that PGRL1 is crucial for acclimation to high light and anoxia in both organisms. Moreover, the data generated for the C. reinhardtii double mutant clearly showed a complementary role of PGRL1 and LHCSR3 in managing high light stress response. We conclude that both proteins are needed for photoprotection and for survival under low oxygen, underpinning a tight link between CEF and NPQ in oxygenic photosynthesis. Given the complementarity of the energy-dependent component of NPQ (qE) and PGRL1-mediated CEF, we suggest that PGRL1 is a capacitor linked to the evolution of the PSII subunit S-dependent qE in terrestrial plants.
    Keywords: Biological sciences -- Biology -- Botany ; Physical sciences -- Physics -- Microphysics ; Health sciences -- Medical conditions -- Symptoms ; Biological sciences -- Biology -- Biological adaptation ; Physical sciences -- Physics -- Matter ; Biological sciences -- Biology -- Systems biology ; Physical sciences -- Physics -- Microphysics ; Biological sciences -- Biology -- Genetics ; Biological sciences -- Biology -- Botany ; Physical sciences -- Physics -- Microphysics;
    ISSN: 00320889
    E-ISSN: 1532-2548
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 09 October 2018, Vol.115(41), pp.10517-10522
    Description: Photosynthetic linear electron flow (LEF) produces ATP and NADPH, while cyclic electron flow (CEF) exclusively drives photophosphorylation to supply extra ATP. The fine-tuning of linear and cyclic electron transport levels allows photosynthetic organisms to balance light energy absorption with cellular energy requirements under constantly changing light conditions. As LEF and CEF share many electron transfer components, a key question is how the same individual structural units contribute to these two different functional modes. Here, we report the structural identification of a photosystem I (PSI)-light harvesting complex I (LHCI)-cytochrome (cyt) bf supercomplex isolated from the unicellular alga under anaerobic conditions, which induces CEF. This provides strong evidence for the model that enhanced CEF is induced by the formation of CEF supercomplexes, when stromal electron carriers are reduced, to generate additional ATP. The additional identification of PSI-LHCI-LHCII complexes is consistent with recent findings that both CEF enhancement and state transitions are triggered by similar conditions, but can occur independently from each other. Single molecule fluorescence correlation spectroscopy indicates a physical association between cyt bf and fluorescent chlorophyll containing PSI-LHCI supercomplexes. Single particle analysis identified top-view projections of the corresponding PSI-LHCI-cyt bf supercomplex. Based on molecular modeling and mass spectrometry analyses, we propose a model in which dissociation of LHCA2 and LHCA9 from PSI supports the formation of this CEF supercomplex. This is supported by the finding that a knockout mutant has constitutively enhanced CEF.
    Keywords: Chlamydomonas Reinhardtii ; Cyclic Electron Flow ; Cytochrome B6f ; Photosystem I ; Supercomplex ; Electrons ; Photosynthesis ; Chlamydomonas Reinhardtii -- Metabolism ; Cytochrome B6f Complex -- Chemistry ; Light-Harvesting Protein Complexes -- Chemistry ; Multiprotein Complexes -- Chemistry ; Photosystem I Protein Complex -- Chemistry
    ISSN: 00278424
    E-ISSN: 1091-6490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Plant physiology, March 2018, Vol.176(3), pp.2305-2314
    Description: Photosynthetic organisms use sunlight as the primary source of energy to support their metabolism. In eukaryotes, reactions responsible of the conversion of light into chemical energy occur in specific organelles, the chloroplasts. In this study, we showed that mitochondria also have a seminal influence on cells' energy metabolism and on photosynthetic reactions. This is illustrated by the observation that the strong photosensitivity of cells depleted of the chloroplast protein PGRL1 was rescued by the introduction of a mitochondrial mutation affecting respiratory complex I. Functional analysis showed that such a reduced respiratory activity influenced chloroplast electron transport with consequent overreduction of plastoquinone and donor-side limitation of photosystem I (PSI). As a consequence, damage due to excess light affected more photosystem II (PSII) rather than PSI. Double mutant cells are able to grow under excess illumination, while single are not, thanks to the presence of an efficient repair mechanism of PSII. These results also underline the seminal biological relevance of the regulation of electron transport reactions within the photosynthetic complexes. Photosynthetic organisms evolved a strategy to respond to excess light where damage is targeting preferentially to a specific complex, PSII. Cells are able to endure extensive damage targeting this complex thanks to an efficient repair mechanisms, while if PSI is affected, there are drastic consequences on growth.
    Keywords: Chlamydomonas Reinhardtii -- Physiology ; Mitochondria -- Metabolism ; Photosynthesis -- Physiology
    ISSN: 00320889
    E-ISSN: 1532-2548
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Plant physiology, May 2014, Vol.165(1), pp.438-52
    Description: The Chlamydomonas reinhardtii proton gradient regulation5 (Crpgr5) mutant shows phenotypic and functional traits similar to mutants in the Arabidopsis (Arabidopsis thaliana) ortholog, Atpgr5, providing strong evidence for conservation of PGR5-mediated cyclic electron flow (CEF). Comparing the Crpgr5 mutant with the wild type, we discriminate two pathways for CEF and determine their maximum electron flow rates. The PGR5/proton gradient regulation-like1 (PGRL1) ferredoxin (Fd) pathway, involved in recycling excess reductant to increase ATP synthesis, may be controlled by extreme photosystem I acceptor side limitation or ATP depletion. Here, we show that PGR5/PGRL1-Fd CEF functions in accordance with an ATP/redox control model. In the absence of Rubisco and PGR5, a sustained electron flow is maintained with molecular oxygen instead of carbon dioxide serving as the terminal electron acceptor. When photosynthetic control is decreased, compensatory alternative pathways can take the full load of linear electron flow. In the case of the ATP synthase pgr5 double mutant, a decrease in photosensitivity is observed compared with the single ATPase-less mutant that we assign to a decreased proton motive force. Altogether, our results suggest that PGR5/PGRL1-Fd CEF is most required under conditions when Fd becomes overreduced and photosystem I is subjected to photoinhibition. CEF is not a valve; it only recycles electrons, but in doing so, it generates a proton motive force that controls the rate of photosynthesis. The conditions where the PGR5 pathway is most required may vary in photosynthetic organisms like C. reinhardtii from anoxia to high light to limitations imposed at the level of carbon dioxide fixation.
    Keywords: Protons ; Adenosine Triphosphatases -- Metabolism ; Adenosine Triphosphate -- Pharmacology ; Chlamydomonas Reinhardtii -- Metabolism ; Mutation -- Genetics ; Plant Proteins -- Metabolism
    ISSN: 00320889
    E-ISSN: 1532-2548
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Plant physiology, June 2015, Vol.168(2), pp.615-34
    Description: In plants and algae, the serine/threonine kinase STN7/STT7, orthologous protein kinases in Chlamydomonas reinhardtii and Arabidopsis (Arabidopsis thaliana), respectively, is an important regulator in acclimation to changing light environments. In this work, we assessed STT7-dependent protein phosphorylation under high light in C. reinhardtii, known to fully induce the expression of light-harvesting complex stress-related protein3 (LHCSR3) and a nonphotochemical quenching mechanism, in relationship to anoxia where the activity of cyclic electron flow is stimulated. Our quantitative proteomics data revealed numerous unique STT7 protein substrates and STT7-dependent protein phosphorylation variations that were reliant on the environmental condition. These results indicate that STT7-dependent phosphorylation is modulated by the environment and point to an intricate chloroplast phosphorylation network responding in a highly sensitive and dynamic manner to environmental cues and alterations in kinase function. Functionally, the absence of the STT7 kinase triggered changes in protein expression and photoinhibition of photosystem I (PSI) and resulted in the remodeling of photosynthetic complexes. This remodeling initiated a pronounced association of LHCSR3 with PSI-light harvesting complex I (LHCI)-ferredoxin-NADPH oxidoreductase supercomplexes. Lack of STT7 kinase strongly diminished PSII-LHCII supercomplexes, while PSII core complex phosphorylation and accumulation were significantly enhanced. In conclusion, our study provides strong evidence that the regulation of protein phosphorylation is critical for driving successful acclimation to high light and anoxic growth environments and gives new insights into acclimation strategies to these environmental conditions.
    Keywords: Environment ; Photosynthesis ; Chlamydomonas Reinhardtii -- Metabolism ; Multiprotein Complexes -- Metabolism ; Plant Proteins -- Metabolism
    ISSN: 00320889
    E-ISSN: 1532-2548
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: PLoS ONE, 2013, Vol.8(4)
    Description: Single cell green algae (microalgae) are rapidly emerging as a platform for the production of sustainable fuels. Solar-driven H 2 production from H 2 O theoretically provides the highest-efficiency route to fuel production in microalgae. This is because the H 2 -producing hydrogenase (HYDA) is directly coupled to the photosynthetic electron transport chain, thereby eliminating downstream energetic losses associated with the synthesis of carbohydrate and oils (feedstocks for methane, ethanol and oil-based fuels). Here we report the simultaneous knock-down of three light-harvesting complex proteins (LHCMB1, 2 and 3) in the high H 2 -producing Chlamydomonas reinhardtii mutant Stm6Glc4 using an RNAi triple knock-down strategy. The resultant Stm6Glc4L01 mutant exhibited a light green phenotype, reduced expression of LHCBM1 (20.6% ±0.27%), LHCBM2 (81.2% ±0.037%) and LHCBM3 (41.4% ±0.05%) compared to 100% control levels, and improved light to H 2 (180%) and biomass (165%) conversion efficiencies. The improved H 2 production efficiency was achieved at increased solar flux densities (450 instead of ∼100 µE m −2 s −1 ) and high cell densities which are best suited for microalgae production as light is ideally the limiting factor. Our data suggests that the overall improved photon-to-H 2 conversion efficiency is due to: 1) reduced loss of absorbed energy by non-photochemical quenching (fluorescence and heat losses) near the photobioreactor surface; 2) improved light distribution in the reactor; 3) reduced photoinhibition; 4) early onset of HYDA expression and 5) reduction of O 2 -induced inhibition of HYDA. The Stm6Glc4L01 phenotype therefore provides important insights for the development of high-efficiency photobiological H 2 production systems.
    Keywords: Research Article ; Agriculture ; Biology
    E-ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Journal of visualized experiments : JoVE, 13 March 2014(85)
    Description: The introduced protocol provides a tool for the analysis of multiprotein complexes in the thylakoid membrane, by revealing insights into complex composition under different conditions. In this protocol the approach is demonstrated by comparing the composition of the protein complex responsible for cyclic electron flow (CEF) in Chlamydomonas reinhardtii, isolated from genetically different strains. The procedure comprises the isolation of thylakoid membranes, followed by their separation into multiprotein complexes by sucrose density gradient centrifugation, SDS-PAGE, immunodetection and comparative, quantitative mass spectrometry (MS) based on differential metabolic labeling ((14)N/(15)N) of the analyzed strains. Detergent solubilized thylakoid membranes are loaded on sucrose density gradients at equal chlorophyll concentration. After ultracentrifugation, the gradients are separated into fractions, which are analyzed by mass-spectrometry based on equal volume. This approach allows the investigation of the composition within the gradient fractions and moreover to analyze the migration behavior of different proteins, especially focusing on ANR1, CAS, and PGRL1. Furthermore, this method is demonstrated by confirming the results with immunoblotting and additionally by supporting the findings from previous studies (the identification and PSI-dependent migration of proteins that were previously described to be part of the CEF-supercomplex such as PGRL1, FNR, and cyt f). Notably, this approach is applicable to address a broad range of questions for which this protocol can be adopted and e.g. used for comparative analyses of multiprotein complex composition isolated from distinct environmental conditions.
    Keywords: Mass Spectrometry -- Methods ; Multiprotein Complexes -- Analysis
    E-ISSN: 1940-087X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Photosynthesis Research, 2017, Vol.134(3), pp.291-306
    Description: Ferredoxins (FDX) and the FDX:NADP + oxidoreductase (FNR) represent a key junction of electron transport downstream of photosystem I (PSI). Dynamic recruitment of FNR to the thylakoid membrane has been considered as a potential mechanism to define the fate of photosynthetically derived electrons. In this study, we investigated the functional importance of the association of FNR with the photosynthetic apparatus in Chlamydomonas reinhardtii . In vitro assays based on NADP + photoreduction measurements as well as NMR chemical shift perturbation analyses showed that FNR preferentially interacts with FDX1 compared to FDX2. Notably, binding of FNR to a PSI supercomplex further enhanced this preference for FDX1 over FDX2, suggesting that FNR is potentially capable of channelling electrons towards distinct routes. NADP + photoreduction assays and immunoblotting revealed that the association of FNR with the thylakoid membrane including the PSI supercomplex is impaired in the absence of Proton Gradient Regulation 5 (PGR5) and/or Proton Gradient Regulation 5-Like photosynthetic phenotype 1 (PGRL1), implying that both proteins, directly or indirectly, contribute to the recruitment of FNR to the thylakoid membrane. As assessed via in vivo absorption spectroscopy and immunoblotting, PSI was the primary target of photodamage in response to high-light stress in the absence of PGR5 and/or PGRL1. Anoxia preserved the activity of PSI, pointing to enhanced electron donation to O 2 as the source of the observed PSI inactivation and degradation. These findings establish another perspective on PGR5/PGRL1 knockout-related phenotypes and potentially interconnect FNR with the regulation of photosynthetic electron transport and PSI photoprotection in C. reinhardtii .
    Keywords: Chlamydomonas reinhardtii ; Electron transport regulation ; Ferredoxin:NADP oxidoreductase ; Ferredoxin ; Proton Gradient Regulation 5 ; PGR5-like photosynthetic phenotype 1
    ISSN: 0166-8595
    E-ISSN: 1573-5079
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Journal of Plant Physiology, 19 June 2014, Vol.165(4), pp.1604-1617
    Description: To investigate the functional importance of Proton Gradient Regulation5-Like1 (PGRL1) for photosynthetic performances in the moss Physcomitrella patens, we generated a pgrl1 knockout mutant. Functional analysis revealed diminished nonphotochemical quenching (NPQ) as well as decreased capacity...
    Keywords: Life Sciences ; Moss ; Physcomitrella Patens ; Algae ; Chlamydomonas Rheinhardtii ; Stress Acclimation ; High Light ; Anoxia ; Photosynthesis ; Photoprotection ; Cyclic Electron Flow ; Photosystem II ; Botany
    ISSN: 0176-1617
    Source: Hyper Article en Ligne (CCSd)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: BBA - Bioenergetics, September 2018, Vol.1859, pp.e34-e34
    Keywords: Chemistry
    ISSN: 0005-2728
    E-ISSN: 1879-2650
    Source: ScienceDirect Journals (Elsevier)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages