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  1 / 2159 MEDLINE  
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[PMID]:29066393
[Au] Autor:Badshah SL; Sun J; Mula S; Gorka M; Baker P; Luthra R; Lin S; van der Est A; Golbeck JH; Redding KE
[Ad] Endereço:School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
[Ti] Título:Mutations in algal and cyanobacterial Photosystem I that independently affect the yield of initial charge separation in the two electron transfer cofactor branches.
[So] Source:Biochim Biophys Acta;1859(1):42-55, 2018 01.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:In Photosystem I, light-induced electron transfer can occur in either of two symmetry-related branches of cofactors, each of which is composed of a pair of chlorophylls (ec2 /ec3 or ec2 /ec3 ) and a phylloquinone (PhQ or PhQ ). The axial ligand to the central Mg of the ec2 and ec2 chlorophylls is a water molecule that is also H-bonded to a nearby Asn residue. Here, we investigate the importance of this interaction for charge separation by converting each of the Asn residues to a Leu in the green alga, Chlamydomonas reinhardtii, and the cyanobacterium, Synechocystis sp. PCC6803, and studying the energy and electron transfer using time-resolved optical and EPR spectroscopy. Nanosecond transient absorbance measurements of the PhQ to F electron transfer show that in both species, the PsaA-N604L mutation (near ec2 ) results in a ~50% reduction in the amount of electron transfer in the B-branch, while the PsaB-N591L mutation (near ec2 ) results in a ~70% reduction in the amount of electron transfer in the A-branch. A diminished quantum yield of P PhQ is also observed in ultrafast optical experiments, but the lower yield does not appear to be a consequence of charge recombination in the nanosecond or microsecond timescales. The most significant finding is that the yield of electron transfer in the unaffected branch did not increase to compensate for the lower yield in the affected branch. Hence, each branch of the reaction center appears to operate independently of the other in carrying out light-induced charge separation.
[Mh] Termos MeSH primário: Proteínas de Bactérias/química
Chlamydomonas reinhardtii/enzimologia
Mutação de Sentido Incorreto
Complexo de Proteína do Fotossistema I/química
Complexo de Proteína do Fotossistema I/genética
Synechocystis/enzimologia
[Mh] Termos MeSH secundário: Substituição de Aminoácidos
Proteínas de Bactérias/genética
Proteínas de Bactérias/metabolismo
Chlamydomonas reinhardtii/genética
Transporte de Elétrons
Complexo de Proteína do Fotossistema I/metabolismo
Synechocystis/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Photosystem I Protein Complex)
[Em] Mês de entrada:1803
[Cu] Atualização por classe:180309
[Lr] Data última revisão:
180309
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171026
[St] Status:MEDLINE


  2 / 2159 MEDLINE  
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[PMID]:29253814
[Au] Autor:Faseela P; Puthur JT
[Ad] Endereço:Plant Physiology and Biochemistry Division, Department of Botany, University of Calicut, Malappuram, Kerala 673635, India.
[Ti] Título:The imprints of the high light and UV-B stresses in Oryza sativa L. 'Kanchana' seedlings are differentially modulated.
[So] Source:J Photochem Photobiol B;178:551-559, 2018 Jan.
[Is] ISSN:1873-2682
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:High light and ultraviolet-B radiation (UV-B) are generally considered to have negative impact on photosynthesis and plant growth. The present study evaluates the tolerance potential of three cultivars of Oryza sativa L. (Kanchana, Mattatriveni and Harsha) seedlings towards high light and UV-B stress on the basis of photosynthetic pigment degradation, chlorophyll a fluorescence parameters and rate of lipid peroxidation, expressed by malondialdehyde content. Surprisingly, it was revealed that Kanchana was the most sensitive cultivar towards high light and at the same time it was the most tolerant cultivar towards UV-B stress. This contrasting feature of Kanchana towards high light and UV-B tolerance was further studied by analyzing photosystem (PS) I and II activity, mitochondrial activity, chlorophyll a fluorescence transient, enzymatic and non-enzymatic antioxidant defense system. Due to the occurrence of more PS I and PSII damages, the inhibition of photochemical efficiency and emission of dissipated energy as heat or fluorescence per PSII reaction center was higher upon high light exposure than UV-B treatments in rice seedlings of Kanchana. The mitochondrial activity was also found to be drastically altered upon high light as compared to UV-B treatments. The UV-B induced accumulation of non-enzymatic antioxidants (proline, total phenolics, sugar and ascorbate) and enzymatic antioxidants (ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase and glutathione reductase) in rice seedlings than those subjected to high light exposure afforded more efficient protection against UV-B radiation in rice seedlings. Our results proved that high tolerance of Kanchana towards UV-B than high light treatments, correlated linearly with the protected photosynthetic and mitochondrial machinery which was provided by upregulation of antioxidants particularly by total phenolics, ascorbate and ascorbate peroxidase in rice seedlings. Data presented in this study conclusively proved that rice cultivar Kanchana respond to different environmental signals independently and tolerance mechanisms to individual stress factors was also varied.
[Mh] Termos MeSH primário: Oryza/efeitos da radiação
Raios Ultravioleta
[Mh] Termos MeSH secundário: Antioxidantes/metabolismo
Ascorbato Peroxidases/metabolismo
Ácido Ascórbico/metabolismo
Clorofila/química
Clorofila/metabolismo
Malondialdeído/metabolismo
Mitocôndrias/metabolismo
Mitocôndrias/efeitos da radiação
Oryza/crescimento & desenvolvimento
Fenóis/metabolismo
Fotossíntese/efeitos da radiação
Complexo de Proteína do Fotossistema I/metabolismo
Complexo de Proteína do Fotossistema II/metabolismo
Prolina/metabolismo
Plântulas/metabolismo
Plântulas/efeitos da radiação
Espectrometria de Fluorescência
Regulação para Cima/efeitos da radiação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Antioxidants); 0 (Phenols); 0 (Photosystem I Protein Complex); 0 (Photosystem II Protein Complex); 1406-65-1 (Chlorophyll); 4Y8F71G49Q (Malondialdehyde); 9DLQ4CIU6V (Proline); EC 1.11.1.11 (Ascorbate Peroxidases); PQ6CK8PD0R (Ascorbic Acid); YF5Q9EJC8Y (chlorophyll a)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180212
[Lr] Data última revisão:
180212
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171219
[St] Status:MEDLINE


  3 / 2159 MEDLINE  
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[PMID]:27770413
[Au] Autor:Stine KJ; Jefferson K; Shulga OV
[Ad] Endereço:Department of Chemistry and Biochemistry, Center for Nanoscience, University of Missouri-Saint Louis, One University Boulevard, Saint Louis, MO, 63121-4400, USA. kstine@umsl.edu.
[Ti] Título:Nanoporous Gold for Enzyme Immobilization.
[So] Source:Methods Mol Biol;1504:37-60, 2017.
[Is] ISSN:1940-6029
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules, especially enzymes. The material provides a high surface area form of gold that is suitable for physisorption or for covalent modification by self-assembled monolayers. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing between 20 and 50 % atomic composition of gold and less noble element(s) by dealloying procedures. Materials resembling NPG can be prepared by hydrothermal and electrodeposition methods. Related high surface area gold structures have been prepared using templating approaches. Covalent enzyme immobilization can be achieved by first forming a self-assembled monolayer on NPG bearing a terminal reactive functional group followed by conjugation to the enzyme through amide linkages to lysine residues. Enzymes can also be entrapped by physisorption or immobilized by electrostatic interactions.
[Mh] Termos MeSH primário: Enzimas Imobilizadas/química
Ouro/química
Nanoporos/ultraestrutura
[Mh] Termos MeSH secundário: Acetilcolinesterase/química
Animais
Técnicas Biossensoriais
Técnicas Eletroquímicas
Eletrodos
Estabilidade Enzimática
Glucose Oxidase/química
Peroxidase do Rábano Silvestre/química
Seres Humanos
Imunoconjugados/química
Lacase/química
Complexo de Proteína do Fotossistema I/química
Porosidade
Spinacia oleracea/enzimologia
Eletricidade Estática
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Enzymes, Immobilized); 0 (Immunoconjugates); 0 (Photosystem I Protein Complex); 7440-57-5 (Gold); EC 1.1.3.4 (Glucose Oxidase); EC 1.10.3.2 (Laccase); EC 1.11.1.- (Horseradish Peroxidase); EC 3.1.1.7 (Acetylcholinesterase)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180115
[Lr] Data última revisão:
180115
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161023
[St] Status:MEDLINE


  4 / 2159 MEDLINE  
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[PMID]:29223152
[Au] Autor:Cherepanov DA; Milanovsky GE; Petrova AA; Tikhonov AN; Semenov AY
[Ad] Endereço:Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Moscow, 119992, Russia. tscherepanov@gmail.com.
[Ti] Título:Electron Transfer through the Acceptor Side of Photosystem I: Interaction with Exogenous Acceptors and Molecular Oxygen.
[So] Source:Biochemistry (Mosc);82(11):1249-1268, 2017 Nov.
[Is] ISSN:1608-3040
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:This review considers the state-of-the-art on mechanisms and alternative pathways of electron transfer in photosynthetic electron transport chains of chloroplasts and cyanobacteria. The mechanisms of electron transport control between photosystems (PS) I and II and the Calvin-Benson cycle are considered. The redistribution of electron fluxes between the noncyclic, cyclic, and pseudocyclic pathways plays an important role in the regulation of photosynthesis. Mathematical modeling of light-induced electron transport processes is considered. Particular attention is given to the electron transfer reactions on the acceptor side of PS I and to interactions of PS I with exogenous acceptors, including molecular oxygen. A kinetic model of PS I and its interaction with exogenous electron acceptors has been developed. This model is based on experimental kinetics of charge recombination in isolated PS I. Kinetic and thermodynamic parameters of the electron transfer reactions in PS I are scrutinized. The free energies of electron transfer between quinone acceptors A /A in the symmetric redox cofactor branches of PS I and iron-sulfur clusters F , F , and F have been estimated. The second-order rate constants of electron transfer from PS I to external acceptors have been determined. The data suggest that byproduct formation of superoxide radical in PS I due to the reduction of molecular oxygen in the A site (Mehler reaction) can exceed 0.3% of the total electron flux in PS I.
[Mh] Termos MeSH primário: Transporte de Elétrons
Complexo de Proteína do Fotossistema I/metabolismo
[Mh] Termos MeSH secundário: Cloroplastos/química
Cloroplastos/metabolismo
Cianobactérias/química
Cianobactérias/metabolismo
Proteínas com Ferro-Enxofre/metabolismo
Cinética
Modelos Químicos
Oxigênio/metabolismo
Quinonas/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Iron-Sulfur Proteins); 0 (Photosystem I Protein Complex); 0 (Quinones); S88TT14065 (Oxygen)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180103
[Lr] Data última revisão:
180103
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171211
[St] Status:MEDLINE
[do] DOI:10.1134/S0006297917110037


  5 / 2159 MEDLINE  
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[PMID]:28669508
[Au] Autor:Makita H; Rohani L; Zhao N; Hastings G
[Ad] Endereço:Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA.
[Ti] Título:Quinones in the A binding site in photosystem I studied using time-resolved FTIR difference spectroscopy.
[So] Source:Biochim Biophys Acta;1858(9):804-813, 2017 09.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Time-resolved step-scan FTIR difference spectroscopy at low temperature (77 K) has been used to study photosystem I particles with phylloquinone (2-methyl-3-phytyl-1,4-naphthaquinone) and menadione (2-methyl-1,4-naphthaquinone) incorporated into the A binding site. By subtracting spectra for PSI with phylloquinone incorporated from spectra for PSI with menadione incorporated a (menadione - phylloquinone) double difference spectrum was constructed. In the double difference spectrum bands associated with protein vibrational modes effectively cancel, and the bands in the spectrum are primarily associated with the neutral and reduced states of the two quinones in the A binding site. To aid in the assignment of bands in the experimental double difference spectrum, a double difference spectrum was calculated using three-layer ONIOM methods. The calculated and experimental spectra agree well, allowing unambiguous band assignments to be made. The ONIOM calculations show that both quinones in the A binding site are similarly oriented, with only a single hydrogen bond between the C =O quinone carbonyl group and the backbone NH group of a leucine residue. For the semi-quinone species, but not for the neutral species, this hydrogen bond appears to be very strong. Finally, we have for the first time been able to unmask and identify infrared difference bands associated with neutral naphthoquinone species occupying the A binding site in PSI.
[Mh] Termos MeSH primário: Complexo de Proteína do Fotossistema I/química
Quinonas/química
Espectroscopia de Infravermelho com Transformada de Fourier/métodos
Vitamina K 1/metabolismo
[Mh] Termos MeSH secundário: Sítios de Ligação
Modelos Moleculares
Complexo de Proteína do Fotossistema I/metabolismo
Ligação Proteica
Conformação Proteica
Synechocystis/genética
Synechocystis/metabolismo
Vitamina K 2/metabolismo
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Photosystem I Protein Complex); 0 (Quinones); 11032-49-8 (Vitamin K 2); 84-80-0 (Vitamin K 1)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171025
[Lr] Data última revisão:
171025
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170704
[St] Status:MEDLINE


  6 / 2159 MEDLINE  
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[PMID]:28576442
[Au] Autor:Nozue S; Katayama M; Terazima M; Kumazaki S
[Ad] Endereço:Department of Chemistry, Graduate School of Science, Kyoto University, Japan.
[Ti] Título:Comparative study of thylakoid membranes in terminal heterocysts and vegetative cells from two cyanobacteria, Rivularia M-261 and Anabaena variabilis, by fluorescence and absorption spectral microscopy.
[So] Source:Biochim Biophys Acta;1858(9):742-749, 2017 09.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Heterocyst is a nitrogen-fixing cell differentiated from a cell for oxygen-evolving photosynthesis (vegetative cell) in some filamentous cyanobacteria when fixed nitrogen (e.g., ammonia and nitrate) is limited. Heterocysts appear at multiple separated positions in a single filament with an interval of 10-20 cells in some genera (including Anabaena variabilis). In other genera, a single heterocyst appears only at the basal terminal in a filament (including Rivularia M-261). Such morphological diversity may necessitate different properties of heterocysts. However, possible differences in heterocysts have largely remained unexplored due to the minority of heterocysts among major vegetative cells. Here, we have applied spectroscopic microscopy to Rivularia and A. variabilis to analyze their thylakoid membranes in individual cells. Absorption and fluorescence spectral imaging enabled us to estimate concentrations and interconnections of key photosynthetic components like photosystem I (PSI), photosystem II (PSII) and subunits of light-harvesting phycobilisome including phycocyanin (PC). The concentration of PC in heterocysts of Rivularia is far higher than that of A. variabilis. Fluorescence quantum yield of PC in Rivularia heterocysts was found to be virtually the same as those in its vegetative cells, while fluorescence quantum yield of PC in A. variabilis heterocysts was enhanced in comparison with its vegetative cells. PSI concentration in the thylakoid membranes of heterocysts seems to remain nearly the same as those of the vegetative cells in both the species. The average stoichiometric ratio between PSI monomer and PC hexamer in Rivularia heterocysts is estimated to be about 1:1.
[Mh] Termos MeSH primário: Cianobactérias/ultraestrutura
Microscopia/métodos
Tilacoides/ultraestrutura
[Mh] Termos MeSH secundário: Absorção de Radiação
Anabaena variabilis/metabolismo
Anabaena variabilis/efeitos da radiação
Anabaena variabilis/ultraestrutura
Cianobactérias/metabolismo
Cianobactérias/efeitos da radiação
Membranas Intracelulares/ultraestrutura
Luz
Microscopia de Fluorescência
Fixação de Nitrogênio
Complexo de Proteína do Fotossistema I/metabolismo
Complexo de Proteína do Fotossistema I/efeitos da radiação
Ficobilissomas/efeitos da radiação
Ficobilissomas/ultraestrutura
Ficocianina/análise
Especificidade da Espécie
Análise Espectral/métodos
Tilacoides/metabolismo
Tilacoides/efeitos da radiação
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Photosystem I Protein Complex); 0 (Phycobilisomes); 11016-15-2 (Phycocyanin)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171025
[Lr] Data última revisão:
171025
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170604
[St] Status:MEDLINE


  7 / 2159 MEDLINE  
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[PMID]:28559282
[Au] Autor:Strand DD; Fisher N; Kramer DM
[Ad] Endereço:From the MSU-DOE Plant Research Laboratory and.
[Ti] Título:The higher plant plastid NAD(P)H dehydrogenase-like complex (NDH) is a high efficiency proton pump that increases ATP production by cyclic electron flow.
[So] Source:J Biol Chem;292(28):11850-11860, 2017 Jul 14.
[Is] ISSN:1083-351X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Cyclic electron flow around photosystem I (CEF) is critical for balancing the photosynthetic energy budget of the chloroplast by generating ATP without net production of NADPH. We demonstrate that the chloroplast NADPH dehydrogenase complex, a homolog to respiratory Complex I, pumps approximately two protons from the chloroplast stroma to the lumen per electron transferred from ferredoxin to plastoquinone, effectively increasing the efficiency of ATP production via CEF by 2-fold compared with CEF pathways involving non-proton-pumping plastoquinone reductases. By virtue of this proton-pumping stoichiometry, we hypothesize that NADPH dehydrogenase not only efficiently contributes to ATP production but operates near thermodynamic reversibility, with potentially important consequences for remediating mismatches in the thylakoid energy budget.
[Mh] Termos MeSH primário: Arabidopsis/enzimologia
Cloroplastos/enzimologia
Modelos Moleculares
NADPH Desidrogenase/metabolismo
Complexo de Proteína do Fotossistema I/metabolismo
Folhas de Planta/enzimologia
Spinacia oleracea/enzimologia
[Mh] Termos MeSH secundário: Trifosfato de Adenosina/metabolismo
Algoritmos
Biocatálise
Domínio Catalítico
Transporte de Elétrons
Ferredoxinas/química
Ferredoxinas/metabolismo
Cinética
NADPH Desidrogenase/química
NADPH Desidrogenase/isolamento & purificação
Complexo de Proteína do Fotossistema I/química
Complexo de Proteína do Fotossistema I/isolamento & purificação
Plastoquinona/química
Plastoquinona/metabolismo
Conformação Proteica
Domínios e Motivos de Interação entre Proteínas
Subunidades Proteicas/química
Subunidades Proteicas/isolamento & purificação
Subunidades Proteicas/metabolismo
Especificidade da Espécie
Termodinâmica
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Ferredoxins); 0 (Photosystem I Protein Complex); 0 (Protein Subunits); 8L70Q75FXE (Adenosine Triphosphate); EC 1.6.99.1 (NADPH Dehydrogenase); OAC30J69CN (Plastoquinone)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170803
[Lr] Data última revisão:
170803
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170601
[St] Status:MEDLINE
[do] DOI:10.1074/jbc.M116.770792


  8 / 2159 MEDLINE  
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[PMID]:28530393
[Au] Autor:Kawashima K; Ishikita H
[Ad] Endereço:Department of Applied Chemistry, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
[Ti] Título:Structural Factors That Alter the Redox Potential of Quinones in Cyanobacterial and Plant Photosystem I.
[So] Source:Biochemistry;56(24):3019-3028, 2017 Jun 20.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Using the cyanobacterial and plant photosystem I (PSI) crystal structures and by considering the protonation states of all titratable residues, redox potentials (E ) of the two phylloquinones-A and A -were calculated. The calculated E values were E (A ) = -773 mV and E (A ) = -818 mV for the plant PSI structure and E (A ) = -612 mV and E (A ) = -719 mV for the cyanobacterial PSI structure. Our analysis of the PSI crystal structures suggested that the side-chain orientations of Lys-B542 and Gln-B678 in the cyanobacterial crystal structure differ from these side-chain orientations in the plant crystal structure. Quantum mechanical/molecular mechanical calculations indicated that the geometry of the cyanobacterial PSI crystal structure was best described as the conformation where Asp-B575 is protonated and A is reduced to A , which might represent the high-potential A form ( Rutherford, A. W., Osyczka, A., Rappaport, F. ( 2012 ) FEBS Lett. 586 , 603 - 616 ). Reorienting the Lys-B542 and Gln-B678 side-chains and rearranging the H-bond pattern of the water cluster near Asp-B575 lowered the E to E (A ) = -718 mV and E (A ) = -795 mV. It seems possible that PSI has two conformations: the high-potential A form and the low-potential A form.
[Mh] Termos MeSH primário: Ervilhas/enzimologia
Complexo de Proteína do Fotossistema I/metabolismo
Quinonas/química
Synechocystis/enzimologia
[Mh] Termos MeSH secundário: Modelos Moleculares
Simulação de Dinâmica Molecular
Estrutura Molecular
Oxirredução
Teoria Quântica
Quinonas/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Photosystem I Protein Complex); 0 (Quinones)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170926
[Lr] Data última revisão:
170926
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170523
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.7b00082


  9 / 2159 MEDLINE  
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[PMID]:28499880
[Au] Autor:Chukhutsina VU; Fristedt R; Morosinotto T; Croce R
[Ad] Endereço:Biophysics of Photosynthesis, Dep. of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, the Netherlands.
[Ti] Título:Photoprotection strategies of the alga Nannochloropsis gaditana.
[So] Source:Biochim Biophys Acta;1858(7):544-552, 2017 07.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Nannochloropsis spp. are algae with high potential for biotechnological applications due to their capacity to accumulate lipids. However, little is known about their photosynthetic apparatus and acclimation/photoprotective strategies. In this work, we studied the mechanisms of non-photochemical quenching (NPQ), the fast response to high light stress, in Nannochloropsis gaditana by "locking" the cells in six different states during quenching activation and relaxation. Combining biochemical analysis with time-resolved fluorescence spectroscopy, we correlated each NPQ state with the presence of two well-known NPQ components: de-epoxidized xanthophylls and stress-related antenna proteins (LHCXs). We demonstrated that after exposure to strong light, the rapid quenching that takes place in the antennas of both photosystems was associated with the presence of LHCXs. At later stages, quenching occurs mainly in the antennas of PSII and correlates with the amount of de-epoxidised xanthophylls. We also observed changes in the distribution of excitation energy between photosystems, which suggests redistribution of excitation between photosystems as part of the photo-protective strategy. A multistep model for NPQ induction and relaxation in N. gaditana is discussed.
[Mh] Termos MeSH primário: Estramenópilas/fisiologia
[Mh] Termos MeSH secundário: Proteínas de Algas/química
Proteínas de Algas/isolamento & purificação
Proteínas de Algas/fisiologia
Fluorescência
Luz
Complexos de Proteínas Captadores de Luz/química
Complexos de Proteínas Captadores de Luz/fisiologia
Complexo de Proteína do Fotossistema I/metabolismo
Complexo de Proteína do Fotossistema II/metabolismo
Tolerância a Radiação/fisiologia
Espectrometria de Fluorescência
Estramenópilas/química
Estramenópilas/efeitos da radiação
Xantofilas/química
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Algal Proteins); 0 (Light-Harvesting Protein Complexes); 0 (Photosystem I Protein Complex); 0 (Photosystem II Protein Complex); 0 (Xanthophylls)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171027
[Lr] Data última revisão:
171027
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170514
[St] Status:MEDLINE


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[PMID]:28478116
[Au] Autor:Vajravel S; Kis M; Klodawska K; Laczko-Dobos H; Malec P; Kovács L; Gombos Z; Toth TN
[Ad] Endereço:Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary. Electronic address: vajravel.sindhujaa@brc.mta.hu.
[Ti] Título:Zeaxanthin and echinenone modify the structure of photosystem I trimer in Synechocystis sp. PCC 6803.
[So] Source:Biochim Biophys Acta;1858(7):510-518, 2017 07.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:The function of xanthophylls in the organisation and structure of the photosynthetic complexes is not completely clarified yet. Recently, we observed a reduced level of the photosystem oligomers upon xanthophyll deficiency, although xanthophylls are not considered to be part of the photosynthetic complexes of cyanobacteria. The present study aimed at further investigating the relationship between xanthophylls and photosytem I (PSI) complex in the cyanobacterium Synechocystis sp. PCC 6803. Interestingly, we recorded the presence of echinenone and zeaxanthin in the isolated PSI trimers. These two xanthophyll species are among the most abundant xanthophylls in this cyanobacterial species. Various xanthophyll biosynthesis mutants were used to investigate the specific role of these xanthophylls. Our spectroscopic results revealed specific structural changes manifested in altered pigment-pigment or pigment-protein interactions within PSI complex in the absence of zeaxanthin and echinenone. These structural modifications of the complexes seem to destabilize the PSI trimeric complexes and eventually result in an increased propensity for monomerization. Our results clearly demonstrate that xanthophylls are important for the fine-tuning of the PSI trimer structure. These xanthophylls could be part of the complex or be embedded in the membrane in the vicinity of PSI.
[Mh] Termos MeSH primário: Proteínas de Bactérias/química
Carotenoides/fisiologia
Complexo de Proteína do Fotossistema I/química
Synechocystis/metabolismo
Zeaxantinas/fisiologia
[Mh] Termos MeSH secundário: Proteínas de Bactérias/isolamento & purificação
Proteínas de Bactérias/metabolismo
Centrifugação com Gradiente de Concentração
Dicroísmo Circular
Complexo de Proteína do Fotossistema I/isolamento & purificação
Complexo de Proteína do Fotossistema I/metabolismo
Pigmentos Biológicos/análise
Ligação Proteica
Multimerização Proteica
Espectrometria de Fluorescência
Tilacoides/química
beta Caroteno/análise
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Photosystem I Protein Complex); 0 (Pigments, Biological); 0 (Zeaxanthins); 01YAE03M7J (beta Carotene); 36-88-4 (Carotenoids); LJ5IO02MNQ (echinenone)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171027
[Lr] Data última revisão:
171027
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170508
[St] Status:MEDLINE



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