Base de dados : MEDLINE
Pesquisa : G02.765 [Categoria DeCS]
Referências encontradas : 761 [refinar]
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[PMID]:29045413
[Au] Autor:Korzeniewski B
[Ad] Endereço:Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
[Ti] Título:Contribution of proton leak to oxygen consumption in skeletal muscle during intense exercise is very low despite large contribution at rest.
[So] Source:PLoS One;12(10):e0185991, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:A computer model was used to simulate the dependence of protonmotive force (Δp), proton leak and phenomenological (involving proton leak) ATP/O2 ratio on work intensity in skeletal muscle. Δp, NADH and proton leak decreased with work intensity. The contribution of proton leak to oxygen consumption ([Formula: see text]) decreased from about 60% at rest to about 3 and 1% at moderate and heavy/severe exercise, respectively, while the ATP/O2 ratio increased from 2.1 to 5.5 and 5.7. A two-fold increase in proton leak activity or its decrease to zero decreased/increased the ATP/O2 ratio by only about 3 and 1% during moderate and heavy/severe exercise, respectively. The low contribution of proton leak to [Formula: see text] in intensively working skeletal muscle was mostly caused by a huge increase in ATP usage intensity during rest-to-work transition, while OXPHOS, and thus oxidative ATP supply and [Formula: see text] related to it, was mostly stimulated by high each-step activation (ESA) of OXPHOS complexes. The contribution of proton leak to [Formula: see text] and ATP/O2 ratio in isolated mitochondria should not be directly extrapolated to working muscle, as mitochondria lack ESA, at least in the absence of Ca2+, and therefore [Formula: see text] cannot be elevated as much as in intact muscle.
[Mh] Termos MeSH primário: Exercício/fisiologia
Músculo Esquelético/fisiologia
Consumo de Oxigênio/fisiologia
Prótons
Descanso/fisiologia
[Mh] Termos MeSH secundário: Difosfato de Adenosina/farmacologia
Trifosfato de Adenosina/biossíntese
Seres Humanos
Força Próton-Motriz
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Protons); 61D2G4IYVH (Adenosine Diphosphate); 8L70Q75FXE (Adenosine Triphosphate)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171031
[Lr] Data última revisão:
171031
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171019
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0185991


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[PMID]:28698674
[Au] Autor:Li L; Kromann S; Olsen JE; Svenningsen SW; Olsen RH
[Ad] Endereço:College of Light Industry and Food Sciences, South China University of Technology, Frederiksberg C, Denmark.
[Ti] Título:Insight into synergetic mechanisms of tetracycline and the selective serotonin reuptake inhibitor, sertraline, in a tetracycline-resistant strain of Escherichia coli.
[So] Source:J Antibiot (Tokyo);70(9):944-953, 2017 Aug.
[Is] ISSN:0021-8820
[Cp] País de publicação:Japan
[La] Idioma:eng
[Ab] Resumo:Sertraline, an antidepressive drug, has been reported to inhibit general bacterial efflux pumps. In the present study, we report for the first time a synergistic effect of sertraline and tetracycline in a TetA-encoded tetracycline-resistant strain of Escherichia coli. Synergy between sertraline and tetracycline in an E. coli strain with TetA-mediated tetracycline resistance (E. coli APEC_O2) was assessed by the MIC and checkerboard assays. The global transcriptome of E. coli APEC_O2 exposed to ½ MIC concentrations of sertraline and/or tetracycline was analyzed to elucidate the interaction mechanism between sertraline and tetracycline. The fractional inhibitory concentration index for tetracycline and sertraline in E. coli APEC_O2 was 0.5. In addition, in the presence of ½ MIC of sertraline, the sensitivity of E. coli APEC_O2 to tetracycline could be restored according to clinical standards (from 64 to 4 mg l ). RNA data suggest changes in respiration that is likely to decrease intracellular pH and thereby the proton-motive force, which provides the energy for the tetracycline efflux pump. Furthermore, sertraline and tetracycline may induce a change from oxidation to fermentation in the E.coli, which further decreases pH, resulting in cell death. This study shows that sertraline interacts with tetracycline in a synergistic and AcrAB-TolC pump-independent manner. The combinational treatment was further shown to induce many changes in the global transcriptome, including altered tetA and tetR expression. The results indicate that sertraline may be used as a helper compound with the aim to reverse tetracycline resistance encoded by tetA.
[Mh] Termos MeSH primário: Antibacterianos/farmacologia
Antidepressivos/farmacologia
Escherichia coli/efeitos dos fármacos
Inibidores da Captação de Serotonina/farmacologia
Sertralina/farmacologia
Resistência a Tetraciclina
Tetraciclina/farmacologia
[Mh] Termos MeSH secundário: Antibacterianos/química
Antidepressivos/química
Biologia Computacional
Sinergismo Farmacológico
Transporte de Elétrons/efeitos dos fármacos
Complexo de Proteínas da Cadeia de Transporte de Elétrons/genética
Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo
Escherichia coli/crescimento & desenvolvimento
Proteínas de Escherichia coli/genética
Proteínas de Escherichia coli/metabolismo
Fermentação/efeitos dos fármacos
Perfilação da Expressão Gênica
Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos
Concentração de Íons de Hidrogênio
Concentração Inibidora 50
Líquido Intracelular/efeitos dos fármacos
Líquido Intracelular/metabolismo
Testes de Sensibilidade Microbiana
Viabilidade Microbiana/efeitos dos fármacos
Oxirredução
Força Próton-Motriz/efeitos dos fármacos
Inibidores da Captação de Serotonina/agonistas
Sertralina/agonistas
Tetraciclina/agonistas
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anti-Bacterial Agents); 0 (Antidepressive Agents); 0 (Electron Transport Chain Complex Proteins); 0 (Escherichia coli Proteins); 0 (Serotonin Uptake Inhibitors); F8VB5M810T (Tetracycline); QUC7NX6WMB (Sertraline)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170913
[Lr] Data última revisão:
170913
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170713
[St] Status:MEDLINE
[do] DOI:10.1038/ja.2017.78


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[PMID]:28340510
[Au] Autor:Viljoen A; Dubois V; Girard-Misguich F; Blaise M; Herrmann JL; Kremer L
[Ad] Endereço:Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, UMR 9004, Université de Montpellier, France.
[Ti] Título:The diverse family of MmpL transporters in mycobacteria: from regulation to antimicrobial developments.
[So] Source:Mol Microbiol;104(6):889-904, 2017 Jun.
[Is] ISSN:1365-2958
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Mycobacterial genomes contain large sets of loci encoding membrane proteins that belong to a family of multidrug resistance pumps designated Resistance-Nodulation-Cell Division (RND) permeases. Mycobacterial membrane protein Large (MmpL) transporters represent a subclass of RND transporters known to participate in the export of lipid components across the cell envelope. These surface-exposed lipids with unusual structures play key roles in the physiology of mycobacteria and/or can act as virulence factors and immunomodulators. Defining the substrate specificity of MmpLs and their mechanisms of regulation helps understanding how mycobacteria elaborate their complex cell wall. This review describes the diversity of MmpL proteins in mycobacteria, emphasising their high abundance in a few opportunistic rapid-growing mycobacteria. It reports the conservation of mmpL loci between Mycobacterium tuberculosis and non-tuberculous mycobacteria, useful in predicting the role of MmpLs with unknown functions. Paradoxically, whereas MmpLs participate in drug resistance mechanisms, they represent also attractive pharmacological targets, opening the way for exciting translational applications. The most recent advances regarding structural/functional information are also provided to explain the molecular basis underlying the proton-motive force driven lipid transport. Overall, this review emphasises the Janus-face nature of MmpLs at the crossroads between antibiotic resistance mechanisms and exquisite vulnerability to drugs.
[Mh] Termos MeSH primário: Proteínas de Membrana Transportadoras/metabolismo
Proteínas de Membrana Transportadoras/fisiologia
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Anti-Infecciosos/metabolismo
Proteínas de Bactérias/metabolismo
Transporte Biológico
Membrana Celular/metabolismo
Parede Celular/metabolismo
Regulação Bacteriana da Expressão Gênica
Mycobacterium tuberculosis/metabolismo
Estrutura Terciária de Proteína
Força Próton-Motriz
Fatores de Virulência/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Anti-Infective Agents); 0 (Bacterial Proteins); 0 (Membrane Transport Proteins); 0 (Virulence Factors)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170921
[Lr] Data última revisão:
170921
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170325
[St] Status:MEDLINE
[do] DOI:10.1111/mmi.13675


  4 / 761 MEDLINE  
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[PMID]:28174301
[Au] Autor:Jones AJ; Blaza JN; Varghese F; Hirst J
[Ad] Endereço:From the Medical Research Council Mitochondrial Biology Unit, Cambridge, CB2 0XY, United Kingdom.
[Ti] Título:Respiratory Complex I in and Pumps Four Protons across the Membrane for Every NADH Oxidized.
[So] Source:J Biol Chem;292(12):4987-4995, 2017 Mar 24.
[Is] ISSN:1083-351X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Respiratory complex I couples electron transfer between NADH and ubiquinone to proton translocation across an energy-transducing membrane to support the proton-motive force that drives ATP synthesis. The proton-pumping stoichiometry of complex I ( the number of protons pumped for each two electrons transferred) underpins all mechanistic proposals. However, it remains controversial and has not been determined for any of the bacterial enzymes that are exploited as model systems for the mammalian enzyme. Here, we describe a simple method for determining the proton-pumping stoichiometry of complex I in inverted membrane vesicles under steady-state ADP-phosphorylating conditions. Our method exploits the rate of ATP synthesis, driven by oxidation of NADH or succinate with different sections of the respiratory chain engaged in catalysis as a proxy for the rate of proton translocation and determines the stoichiometry of complex I by reference to the known stoichiometries of complexes III and IV. Using vesicles prepared from mammalian mitochondria (from ) and from the bacterium , we show that four protons are pumped for every two electrons transferred in both cases. By confirming the four-proton stoichiometry for mammalian complex I and, for the first time, demonstrating the same value for a bacterial complex, we establish the utility of complex I as a model system for the mammalian enzyme. is the first system described in which mutagenesis in any complex I core subunit may be combined with quantitative proton-pumping measurements for mechanistic studies.
[Mh] Termos MeSH primário: Trifosfato de Adenosina/metabolismo
Bovinos/metabolismo
Complexo I de Transporte de Elétrons/metabolismo
Paracoccus denitrificans/enzimologia
[Mh] Termos MeSH secundário: Animais
Transporte de Elétrons
Mitocôndrias/metabolismo
NAD/metabolismo
Oxirredução
Fosforilação Oxidativa
Paracoccus denitrificans/metabolismo
Força Próton-Motriz
Prótons
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Protons); 0U46U6E8UK (NAD); 8L70Q75FXE (Adenosine Triphosphate); EC 1.6.5.3 (Electron Transport Complex I)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170922
[Lr] Data última revisão:
170922
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170209
[St] Status:MEDLINE
[do] DOI:10.1074/jbc.M116.771899


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[PMID]:28153920
[Au] Autor:Shimakawa G; Ishizaki K; Tsukamoto S; Tanaka M; Sejima T; Miyake C
[Ad] Endereço:Graduate School of Agricultural Science (G.S., M.T., T.S., C.M.) and Graduate School of Science (K.I., S.T.), Kobe University, Nada, Kobe 657-8501, Japan; and.
[Ti] Título:The Liverwort, , Drives Alternative Electron Flow Using a Flavodiiron Protein to Protect PSI.
[So] Source:Plant Physiol;173(3):1636-1647, 2017 Mar.
[Is] ISSN:1532-2548
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The diffusion efficiency of oxygen in the atmosphere, like that of CO , is approximately 10 times greater than that in aqueous environments. Consequently, terrestrial photosynthetic organisms need mechanisms to protect against potential oxidative damage. The liverwort , a basal land plant, has habitats where it is exposed to both water and the atmosphere. Furthermore, like cyanobacteria, has genes encoding flavodiiron proteins (FLV). In cyanobacteria, FLVs mediate oxygen-dependent alternative electron flow (AEF) to suppress the production of reactive oxygen species. Here, we investigated whether FLVs are required for the protection of photosynthesis in A mutant deficient in the FLV1 isozyme (Δ ) sustained photooxidative damage to photosystem I (PSI) following repetitive short-saturation pulses of light. Compared with the wild type (Takaragaike-1), Δ showed the same photosynthetic oxygen evolution rate but a lower electron transport rate during the induction phase of photosynthesis. Additionally, the reaction center chlorophyll in PSI, P700, was highly reduced in Δ but not in Takaragaike-1. These results indicate that the gene product of drives AEF to oxidize PSI, as in cyanobacteria. Furthermore, FLV-mediated AEF supports the production of a proton motive force to possibly induce the nonphotochemical quenching of chlorophyll fluorescence and suppress electron transport in the cytochrome / complex. After submerging the thalli, a decrease in photosystem II operating efficiency was observed, particularly in Δ , which implies that species living in these sorts of habitats require FLV-mediated AEF.
[Mh] Termos MeSH primário: Flavoproteínas/metabolismo
Marchantia/metabolismo
Complexo de Proteína do Fotossistema I/metabolismo
Proteínas de Plantas/metabolismo
[Mh] Termos MeSH secundário: Clorofila/metabolismo
Complexo Citocromos b6f/genética
Complexo Citocromos b6f/metabolismo
Transporte de Elétrons/genética
Flavoproteínas/genética
Regulação da Expressão Gênica de Plantas
Luz
Marchantia/genética
Mutação
Oxigênio/metabolismo
Fotossíntese/genética
Fotossíntese/efeitos da radiação
Complexo de Proteína do Fotossistema I/genética
Complexo de Proteína do Fotossistema II/genética
Complexo de Proteína do Fotossistema II/metabolismo
Proteínas de Plantas/genética
Força Próton-Motriz/efeitos da radiação
Reação em Cadeia da Polimerase Via Transcriptase Reversa
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Flavoproteins); 0 (Photosystem I Protein Complex); 0 (Photosystem II Protein Complex); 0 (Plant Proteins); 1406-65-1 (Chlorophyll); 9035-40-9 (Cytochrome b6f Complex); S88TT14065 (Oxygen)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171016
[Lr] Data última revisão:
171016
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170204
[St] Status:MEDLINE
[do] DOI:10.1104/pp.16.01038


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[PMID]:27992113
[Au] Autor:Creasy A; Barker G; Carta G
[Ad] Endereço:Department of Chemical Engineering, University of Virginia, Charlottesville, VA, USA.
[Ti] Título:Systematic interpolation method predicts protein chromatographic elution with salt gradients, pH gradients and combined salt/pH gradients.
[So] Source:Biotechnol J;12(3), 2017 Mar.
[Is] ISSN:1860-7314
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:A methodology is presented to predict protein elution behavior from an ion exchange column using both individual or combined pH and salt gradients based on high-throughput batch isotherm data. The buffer compositions are first optimized to generate linear pH gradients from pH 5.5 to 7 with defined concentrations of sodium chloride. Next, high-throughput batch isotherm data are collected for a monoclonal antibody on the cation exchange resin POROS XS over a range of protein concentrations, salt concentrations, and solution pH. Finally, a previously developed empirical interpolation (EI) method is extended to describe protein binding as a function of the protein and salt concentration and solution pH without using an explicit isotherm model. The interpolated isotherm data are then used with a lumped kinetic model to predict the protein elution behavior. Experimental results obtained for laboratory scale columns show excellent agreement with the predicted elution curves for both individual or combined pH and salt gradients at protein loads up to 45 mg/mL of column. Numerical studies show that the model predictions are robust as long as the isotherm data cover the range of mobile phase compositions where the protein actually elutes from the column.
[Mh] Termos MeSH primário: Cromatografia por Troca Iônica
Proteínas/química
Força Próton-Motriz/fisiologia
Cloreto de Sódio/química
[Mh] Termos MeSH secundário: Anticorpos Monoclonais/química
Tampões (Química)
Resinas de Troca de Cátion
Concentração de Íons de Hidrogênio
Modelos Químicos
Ligação Proteica
Proteínas/isolamento & purificação
Sensibilidade e Especificidade
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Antibodies, Monoclonal); 0 (Buffers); 0 (Cation Exchange Resins); 0 (Proteins); 451W47IQ8X (Sodium Chloride)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170328
[Lr] Data última revisão:
170328
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161220
[St] Status:MEDLINE
[do] DOI:10.1002/biot.201600636


  7 / 761 MEDLINE  
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[PMID]:27816676
[Au] Autor:Lyu H; Lazár D
[Ad] Endereço:Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Slechtitelu 27, 78371 Olomouc, Czech Republic.
[Ti] Título:Modeling the light-induced electric potential difference (ΔΨ), the pH difference (ΔpH) and the proton motive force across the thylakoid membrane in C leaves.
[So] Source:J Theor Biol;413:11-23, 2017 Jan 21.
[Is] ISSN:1095-8541
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:A model was constructed which includes electron transport (linear and cyclic and Mehler type reaction) coupled to proton translocation, counter ion movement, ATP synthesis, and Calvin-Benson cycle. The focus is on modeling of the light-induced total electric potential difference (ΔΨ) which in this model originates from the bulk phase electric potential difference (ΔΨ ), the localized electric potential difference (ΔΨ ), as well as the surface electric potential difference (ΔΨ ). The measured dual wavelength transmittance signal (ΔA515-560nm, electrochromic shift) was used as a proxy for experimental ΔΨ. The predictions for theoretical ΔΨ vary with assumed contribution of ΔΨ , which might imply that the measured ΔA515-560nm trace on a long time scale reflects the interplay of the ΔΨ components. Simulations also show that partitioning of proton motive force (pmf) to ΔΨ and ΔpH components is sensitive to the stoichiometric ratio of H /ATP, energy barrier for ATP synthesis, ionic strength, buffer capacity and light intensity. Our model shows that high buffer capacity promotes the establishment of ΔΨ , while the formation of pH minimum is not 'dissipated' but 'postponed' until it reaches the same level as that for low buffer capacity. Under physiologically optimal conditions, the output of the model shows that at steady state in light, the ΔpH component is the main contributor to pmf to drive ATP synthesis while a low ΔΨ persists energizing the membrane. Our model predicts 11mV as the resting electric potential difference across the thylakoid membrane in dark. We suggest that the model presented in this work can be integrated as a module into a more comprehensive model of oxygenic photosynthesis.
[Mh] Termos MeSH primário: Carbono/metabolismo
Luz
Potenciais da Membrana/efeitos da radiação
Modelos Biológicos
Folhas de Planta/metabolismo
Força Próton-Motriz/efeitos da radiação
Tilacoides/metabolismo
Tilacoides/efeitos da radiação
[Mh] Termos MeSH secundário: Tampões (Química)
Simulação por Computador
Transporte de Elétrons
Concentração de Íons de Hidrogênio/efeitos da radiação
Folhas de Planta/efeitos da radiação
Prótons
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Buffers); 0 (Protons); 7440-44-0 (Carbon)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170626
[Lr] Data última revisão:
170626
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161107
[St] Status:MEDLINE


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[PMID]:27621145
[Au] Autor:Nicholls DG
[Ad] Endereço:Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA. Electronic address: dnicholls@buckinstitute.org.
[Ti] Título:The hunt for the molecular mechanism of brown fat thermogenesis.
[So] Source:Biochimie;134:9-18, 2017 Mar.
[Is] ISSN:1638-6183
[Cp] País de publicação:France
[La] Idioma:eng
[Ab] Resumo:This review focuses on research that my colleagues and I carried out from 1972 to 1986 that led to the identification of the original uncoupling protein and the development of the current model for the acute regulation of brown fat thermogenesis. An important consequence of the early stages of this research was the realization that brown fat mitochondria demonstrated the key principles of Peter Mitchell's Chemiosmotic Hypothesis with exquisite precision and simplicity, that a regulatable proton conductance was necessary and sufficient to control respiration and hence thermogenesis, and that fatty acids provided not only the substrate for thermogenesis, but also acted as a self-regulating second (or third) messenger. These studies have provided the basis for 30 years of subsequent research by numerous groups into the structure and mechanism of UCP1, and its role in non-shivering thermogenesis in multiple species, including man.
[Mh] Termos MeSH primário: Adipócitos Marrons/metabolismo
Tecido Adiposo Marrom/metabolismo
Mitocôndrias/metabolismo
Termogênese/fisiologia
Proteína Desacopladora 1/genética
[Mh] Termos MeSH secundário: Adipócitos Marrons/citologia
Tecido Adiposo Marrom/citologia
Animais
Metabolismo Energético/fisiologia
Ácidos Graxos/metabolismo
Regulação da Expressão Gênica
Hibernação/fisiologia
História do Século XX
História do Século XXI
Seres Humanos
Transporte de Íons
Mitocôndrias/genética
Membranas Mitocondriais/metabolismo
Força Próton-Motriz
Proteína Desacopladora 1/história
Proteína Desacopladora 1/metabolismo
[Pt] Tipo de publicação:HISTORICAL ARTICLE; JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Fatty Acids); 0 (Uncoupling Protein 1)
[Em] Mês de entrada:1702
[Cu] Atualização por classe:170216
[Lr] Data última revisão:
170216
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160914
[St] Status:MEDLINE


  9 / 761 MEDLINE  
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[PMID]:27575692
[Au] Autor:Shikanai T; Yamamoto H
[Ad] Endereço:Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 Japan; CREST, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076 Japan. Electronic address: shikanai@pmg.bot.kyoto-u.ac.jp.
[Ti] Título:Contribution of Cyclic and Pseudo-cyclic Electron Transport to the Formation of Proton Motive Force in Chloroplasts.
[So] Source:Mol Plant;10(1):20-29, 2017 Jan 09.
[Is] ISSN:1752-9867
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Photosynthetic electron transport is coupled to proton translocation across the thylakoid membrane, resulting in the formation of a trans-thylakoid proton gradient (ΔpH) and membrane potential (Δψ). Ion transporters and channels localized to the thylakoid membrane regulate the contribution of each component to the proton motive force (pmf). Although both ΔpH and Δψ contribute to ATP synthesis as pmf, only ΔpH downregulates photosynthetic electron transport via the acidification of the thylakoid lumen by inducing thermal dissipation of excessive absorbed light energy from photosystem II antennae and slowing down of the electron transport through the cytochrome b f complex. To optimize the tradeoff between efficient light energy utilization and protection of both photosystems against photodamage, plants have to regulate the pmf amplitude and its components, ΔpH and Δψ. Cyclic electron transport around photosystem I (PSI) is a major regulator of the pmf amplitude by generating pmf independently of the net production of NADPH by linear electron transport. Chloroplast ATP synthase relaxes pmf for ATP synthesis, and its activity should be finely tuned for maintaining the size of the pmf during steady-state photosynthesis. Pseudo-cyclic electron transport mediated by flavodiiron protein (Flv) forms a large electron sink, which is essential for PSI photoprotection in fluctuating light in cyanobacteria. Flv is conserved from cyanobacteria to gymnosperms but not in angiosperms. The Arabidopsis proton gradient regulation 5 (pgr5) mutant is defective in the main pathway of PSI cyclic electron transport. By introducing Physcomitrella patens genes encoding Flvs, the function of PSI cyclic electron transport was substituted by that of Flv-dependent pseudo-cyclic electron transport. In transgenic plants, the size of the pmf was complemented to the wild-type level but the contribution of ΔpH to the total pmf was lower than that in the wild type. In the pgr5 mutant, the size of the pmf was drastically lowered by the absence of PSI cyclic electron transport. In the mutant, ΔpH occupied the majority of pmf, suggesting the presence of a mechanism for the homeostasis of luminal pH in the light. To avoid damage to photosynthetic electron transport by periods of excess solar energy, plants employ an intricate regulatory network involving alternative electron transport pathways, ion transporters/channels, and pH-dependent mechanisms for downregulating photosynthetic electron transport.
[Mh] Termos MeSH primário: Cloroplastos/metabolismo
Força Próton-Motriz
[Mh] Termos MeSH secundário: Arabidopsis
Transporte de Elétrons
Fotossíntese
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171017
[Lr] Data última revisão:
171017
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160831
[St] Status:MEDLINE


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[PMID]:27456428
[Au] Autor:Nietzel T; Mostertz J; Hochgräfe F; Schwarzländer M
[Ad] Endereço:Plant Energy Biology Lab, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Friedrich-Ebert-Allee 144, 53113 Bonn, Germany.
[Ti] Título:Redox regulation of mitochondrial proteins and proteomes by cysteine thiol switches.
[So] Source:Mitochondrion;33:72-83, 2017 Mar.
[Is] ISSN:1872-8278
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Mitochondria are hotspots of cellular redox biochemistry. Respiration as a defining mitochondrial function is made up of a series of electron transfers that are ultimately coupled to maintaining the proton motive force, ATP production and cellular energy supply. The individual reaction steps involved require tight control and flexible regulation to maintain energy and redox balance in the cell under fluctuating demands. Redox regulation by thiol switching has been a long-standing candidate mechanism to support rapid adjustment of mitochondrial protein function at the posttranslational level. Here we review recent advances in our understanding of cysteine thiol switches in the mitochondrial proteome with a focus on their operation in vivo. We assess the conceptual basis for thiol switching in mitochondria and discuss to what extent insights gained from in vitro studies may be valid in vivo, considering thermodynamic, kinetic and structural constraints. We compare functional proteomic approaches that have been used to assess mitochondrial protein thiol switches, including thioredoxin trapping, redox difference gel electrophoresis (redoxDIGE), isotope-coded affinity tag (OxICAT) and iodoacetyl tandem mass tag (iodoTMT) labelling strategies. We discuss conditions that may favour active thiol switching in mitochondrial proteomes in vivo, and appraise recent advances in dissecting their impact using combinations of in vivo redox sensing and quantitative redox proteomics. Finally we focus on four central facets of mitochondrial biology, aging, carbon metabolism, energy coupling and electron transport, exemplifying the current emergence of a mechanistic understanding of mitochondrial regulation by thiol switching in living plants and animals.
[Mh] Termos MeSH primário: Cisteína/metabolismo
Mitocôndrias/fisiologia
Proteínas Mitocondriais/metabolismo
Processamento de Proteína Pós-Traducional
Proteoma/metabolismo
Compostos de Sulfidrila/metabolismo
[Mh] Termos MeSH secundário: Adaptação Fisiológica
Animais
Respiração Celular
Metabolismo Energético
Oxirredução
Plantas
Força Próton-Motriz
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Mitochondrial Proteins); 0 (Proteome); 0 (Sulfhydryl Compounds); K848JZ4886 (Cysteine)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170509
[Lr] Data última revisão:
170509
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160727
[St] Status:MEDLINE



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