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Pesquisa : A11.284.430.214.190.875.700.140.800 [Categoria DeCS]
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[PMID]:29281724
[Au] Autor:Jiang T; Oh ES; Bonea D; Zhao R
[Ad] Endereço:Departments of Biological Sciences and Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada.
[Ti] Título:HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis.
[So] Source:PLoS One;12(12):e0190168, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Arabidopsis plastidic HSP90C is an HSP90 family molecular chaperone that is required for chloroplast development and function. To understand the mechanism of action of HSP90C within the chloroplast, we conducted a yeast two-hybrid screening and revealed it interacts directly with the photosystem II extrinsic protein PsbO1, which performs a canonical function in the thylakoid lumen. To understand the biological significance of HSP90C-PsbO1 interaction, we investigated the role of HSP90C in modulating the stromal and thylakoid distribution of PsbO1GFP fusion protein. Fusion to GFP significantly delays the PsbO1 thylakoid transport and induces a variegation phenotype. Overexpression of HSP90C promotes the thylakoid distribution of PsbO1GFP and alleviates the leaf variegation. By tracking the chloroplast maturation during photomorphogenesis, we observed PsbO1GFP tends to form distinct fluorescent clusters within the stroma with delayed thylakoid membrane biogenesis, while HSP90C overexpression corrects these adverse effects. We also demonstrated that active HSP90C function is specifically required for stable accumulation of mature PsbO1GFP in thylakoid by using specific inhibitor geldanamycin. This study therefore not only identified novel HSP90C interactors, but also reports for the first time that PsbO1 enroute from the cytoplasm to thylakoid lumen is tightly regulated by the HSP90C chaperone complex in plastid stroma; whereas the proper HSP90C homeostasis is also critical for chloroplast maturation and function.
[Mh] Termos MeSH primário: Proteínas de Arabidopsis/metabolismo
Arabidopsis/metabolismo
Cloroplastos/metabolismo
Proteínas de Choque Térmico/metabolismo
Tilacoides/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Arabidopsis Proteins); 0 (Heat-Shock Proteins)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180206
[Lr] Data última revisão:
180206
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171228
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0190168


  2 / 2175 MEDLINE  
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[PMID]:29262360
[Au] Autor:Van Eerden FJ; Melo MN; Frederix PWJM; Marrink SJ
[Ad] Endereço:Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, the Netherlands. Electronic address: floris@vaneerden.eu.
[Ti] Título:Prediction of Thylakoid Lipid Binding Sites on Photosystem II.
[So] Source:Biophys J;113(12):2669-2681, 2017 Dec 19.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The thylakoid membrane has a unique lipid composition, consisting mostly of galactolipids. These thylakoid lipids have important roles in photosynthesis. Here, we investigate to what extent these lipids bind specifically to the Photosystem II complex. To this end, we performed coarse-grain MD simulations of the Photosystem II complex embedded in a thylakoid membrane with realistic composition. Based on >85 µs simulation time, we find that monogalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol lipids are enriched in the annular shell around the protein, and form distinct binding sites. From the analysis of residue contacts, we conclude that electrostatic interactions play an important role in stabilizing these binding sites. Furthermore, we find that chlorophyll a has a prevalent role in the coordination of the lipids. In addition, we observe lipids to diffuse in and out of the plastoquinone exchange cavities, allowing exchange of cocrystallized lipids with the bulk membrane and suggesting a more open nature of the plastoquinone exchange cavity. Together, our data provide a wealth of information on protein-lipid interactions for a key protein in photosynthesis.
[Mh] Termos MeSH primário: Lipídeos de Membrana/metabolismo
Simulação de Dinâmica Molecular
Complexo de Proteína do Fotossistema II/metabolismo
Tilacoides/metabolismo
[Mh] Termos MeSH secundário: Sítios de Ligação
Glicerol/metabolismo
Complexo de Proteína do Fotossistema II/química
Ligação Proteica
Conformação Proteica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Membrane Lipids); 0 (Photosystem II Protein Complex); PDC6A3C0OX (Glycerol)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180102
[Lr] Data última revisão:
180102
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171221
[St] Status:MEDLINE


  3 / 2175 MEDLINE  
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[PMID]:29207281
[Au] Autor:Mazur R; Trzcinska-Danielewicz J; Kozlowski P; Kowalewska L; Rumak I; Shiell BJ; Mostowska A; Michalski WP; Garstka M
[Ad] Endereço:Department of Metabolic Regulation, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland. Electronic address: rmazur@biol.uw.edu.pl.
[Ti] Título:Dark-chilling and subsequent photo-activation modulate expression and induce reversible association of chloroplast lipoxygenase with thylakoid membrane in runner bean (Phaseolus coccineus L.).
[So] Source:Plant Physiol Biochem;122:102-112, 2018 Jan.
[Is] ISSN:1873-2690
[Cp] País de publicação:France
[La] Idioma:eng
[Ab] Resumo:Lipoxygenases (LOXs) are non-haem iron-containing dioxygenases that catalyse oxygenation of polyunsaturated fatty acids. This reaction is the first step in biosynthesis of oxylipins, which play important and diverse roles in stress response. In this study, we identified four LOX genes (PcLOXA, B, C, D) in chilling-sensitive runner bean (Phaseolus coccineus L.) plant and analyzed their expression patterns during long term dark-chilling (4 °C) stress and during day/night (21ºC/4 °C) temperature fluctuations. Three of the four identified LOX genes, namely PcLOXA, PcLOXB and PcLOXD, were induced by wounding stress, while only the PcLOXA was induced by dark-chilling of both detached (wounded) leaves and whole plants. We identified PcLOXA as a chloroplast-targeted LOX protein and investigated its expression during chilling stress in terms of abundance, localization inside chloroplasts and interactions with the thylakoid membranes. The analysis by immunogold electron microscopy has shown that more than 60% of detectable PcLOXA protein was associated with thylakoids, and dark-chilling of leaves resulted in increased amounts of this protein detected within grana margins of thylakoids. This effect was reversible under subsequent photo-activation of chilled leaves. PcLOXA binding to thylakoids is not mediated by the posttranslational modification but rather is based on direct interactions of the protein with membrane lipids; the binding strength increases under dark-chilling conditions.
[Mh] Termos MeSH primário: Temperatura Baixa
Luz
Lipoxigenase/metabolismo
Phaseolus/enzimologia
Proteínas de Plantas/metabolismo
Tilacoides/enzimologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Proteins); EC 1.13.11.12 (Lipoxygenase)
[Em] Mês de entrada:1712
[Cu] Atualização por classe:171226
[Lr] Data última revisão:
171226
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171206
[St] Status:MEDLINE


  4 / 2175 MEDLINE  
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[PMID]:28627163
[Au] Autor:Mizoguchi T; Isaji M; Yamano N; Harada J; Fujii R; Tamiaki H
[Ad] Endereço:Graduate School of Life Sciences, Ritsumeikan University , Kusatsu, Shiga 525-8577, Japan.
[Ti] Título:Molecular Structures and Functions of Chlorophylls-a Esterified with Geranylgeranyl, Dihydrogeranylgeranyl, and Tetrahydrogeranylgeranyl Groups at the 17-Propionate Residue in a Diatom, Chaetoceros calcitrans.
[So] Source:Biochemistry;56(28):3682-3688, 2017 Jul 18.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The 17-propionate ester group of chlorophyll(Chl)-a in some oxygenic phototrophs was investigated using HPLC. Chls-a esterified with partially dehydrogenated forms of a phytyl group were found in fully grown cells of a diatom, Chaetoceros calcitrans: geranylgeranyl (GG), dihydrogeranylgeranyl (DHGG), and tetrahydrogeranylgeranyl (THGG). Chls-a bearing such esterifying groups were reported to be found only in greening processes of higher plants, and thus these Chls-a have been thought to be biosynthetic precursors for phytylated Chl-a. Their molecular structures were unambiguously determined using H and C NMR spectroscopy and mass spectrometry. In particular, the positions of C═C double bonds in DHGG were identified at C2═C3, C6═C7, and C14═C15, and those in THGG were determined to be at C2═C3 and C14═C15. Notably, the present DHGG was different from the previously determined DHGG of bacteriochlorophyll-a in purple bacteria (C2═C3, C10═C11, and C14═C15). Moreover, thylakoid membranes as well as fucoxanthin-chlorophyll-a/c proteins called FCPs were isolated from the diatom, and their Chl-a compositions were analyzed. Chls-a esterified with GG, DHGG, and THGG were detected by HPLC, indicating that such Chls-a were not merely biosynthetic precursors, but photosynthetically active pigments.
[Mh] Termos MeSH primário: Clorofila/química
Diatomáceas/química
Tilacoides/química
[Mh] Termos MeSH secundário: Esterificação
Hordeum/química
Prenilação
Propionatos/análise
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Propionates); 1406-65-1 (Chlorophyll); YF5Q9EJC8Y (chlorophyll a)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170804
[Lr] Data última revisão:
170804
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170620
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.7b00381


  5 / 2175 MEDLINE  
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[PMID]:28608391
[Au] Autor:Bernfur K; Rutsdottir G; Emanuelsson C
[Ad] Endereço:Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Sweden.
[Ti] Título:The chloroplast-localized small heat shock protein Hsp21 associates with the thylakoid membranes in heat-stressed plants.
[So] Source:Protein Sci;26(9):1773-1784, 2017 Sep.
[Is] ISSN:1469-896X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The small heat shock protein (sHsp) chaperones are crucial for cell survival and can prevent aggregation of client proteins that partially unfold under destabilizing conditions. Most investigations on the chaperone activity of sHsps are based on a limited set of thermosensitive model substrate client proteins since the endogenous targets are often not known. There is a high diversity among sHsps with a single conserved ß-sandwich fold domain defining the family, the α-crystallin domain, whereas the N-terminal and C-terminal regions are highly variable in length and sequence among various sHsps and conserved only within orthologues. The endogenous targets are probably also varying among various sHsps, cellular compartments, cell type and organism. Here we have investigated Hsp21, a non-metazoan sHsp expressed in the chloroplasts in green plants which experience huge environmental fluctuations not least in temperature. We describe how Hsp21 can also interact with the chloroplast thylakoid membranes, both when isolated thylakoid membranes are incubated with Hsp21 protein and when plants are heat-stressed. The amount of Hsp21 associated with the thylakoid membranes was precisely determined by quantitative mass spectrometry after metabolic N-isotope labeling of either recombinantly expressed and purified Hsp21 protein or intact Arabidopsis thaliana plants. We found that Hsp21 is among few proteins that become associated with the thylakoid membranes in heat-stressed plants, and that approximately two thirds of the pool of chloroplast Hsp21 is affected. We conclude that for a complete picture of the role of sHsps in plant stress resistance also their association with the membranes should be considered.
[Mh] Termos MeSH primário: Proteínas de Arabidopsis/metabolismo
Arabidopsis/fisiologia
Proteínas de Choque Térmico/metabolismo
Resposta ao Choque Térmico/fisiologia
Tilacoides/metabolismo
[Mh] Termos MeSH secundário: Arabidopsis/metabolismo
Proteínas de Arabidopsis/análise
Proteínas de Arabidopsis/química
Proteínas de Arabidopsis/genética
Cloroplastos/química
Cloroplastos/metabolismo
Escherichia coli/genética
Proteínas de Choque Térmico/análise
Proteínas de Choque Térmico/química
Proteínas de Choque Térmico/genética
Temperatura Alta
Proteínas Recombinantes/análise
Proteínas Recombinantes/química
Proteínas Recombinantes/genética
Proteínas Recombinantes/metabolismo
Tilacoides/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Arabidopsis Proteins); 0 (HSP21 protein, Arabidopsis); 0 (Heat-Shock Proteins); 0 (Recombinant Proteins)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170925
[Lr] Data última revisão:
170925
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170614
[St] Status:MEDLINE
[do] DOI:10.1002/pro.3213


  6 / 2175 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 / 2175 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


  8 / 2175 MEDLINE  
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[PMID]:28429323
[Au] Autor:Durnford DG; Schwartzbach SD
[Ad] Endereço:Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB, Canada, E3B 5A3.
[Ti] Título:Protein Targeting to the Plastid of Euglena.
[So] Source:Adv Exp Med Biol;979:183-205, 2017.
[Is] ISSN:0065-2598
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The lateral transfer of photosynthesis between kingdoms through endosymbiosis is among the most spectacular examples of evolutionary innovation. Euglena, which acquired a chloroplast indirectly through an endosymbiosis with a green alga, represents such an example. As with other endosymbiont-derived plastids from eukaryotes, there are additional membranes that surround the organelle, of which Euglena has three. Thus, photosynthetic genes that were transferred from the endosymbiont to the host nucleus and whose proteins are required in the new plastid, are now faced with targeting and plastid import challenges. Early immunoelectron microscopy data suggested that the light-harvesting complexes, photosynthetic proteins in the thylakoid membrane, are post-translationally targeted to the plastid via the Golgi apparatus, an unexpected discovery at the time. Proteins targeted to the Euglena plastid have complex, bipartite presequences that direct them into the endomembrane system, through the Golgi apparatus and ultimately on to the plastid, presumably via transport vesicles. From transcriptome sequencing, dozens of plastid-targeted proteins were identified, leading to the identification of two different presequence structures. Both have an amino terminal signal peptide followed by a transit peptide for plastid import, but only one of the two classes of presequences has a third domain-the stop transfer sequence. This discovery implied two different transport mechanisms; one where the protein was fully inserted into the lumen of the ER and another where the protein remains attached to, but effectively outside, the endomembrane system. In this review, we will discuss the biochemical and bioinformatic evidence for plastid targeting, discuss the evolution of the targeting system, and ultimately provide a working model for the targeting and import of proteins into the plastid of Euglena.
[Mh] Termos MeSH primário: Euglena/fisiologia
Complexo de Golgi/fisiologia
Membranas Intracelulares/fisiologia
Proteínas de Protozoários/metabolismo
Tilacoides/fisiologia
[Mh] Termos MeSH secundário: Euglena/ultraestrutura
Complexo de Golgi/ultraestrutura
Membranas Intracelulares/ultraestrutura
Transporte Proteico/fisiologia
Proteínas de Protozoários/genética
Tilacoides/ultraestrutura
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Protozoan Proteins)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171024
[Lr] Data última revisão:
171024
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170422
[St] Status:MEDLINE
[do] DOI:10.1007/978-3-319-54910-1_10


  9 / 2175 MEDLINE  
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[PMID]:28252285
[Au] Autor:Palm DM; Agostini A; Tenzer S; Gloeckle BM; Werwie M; Carbonera D; Paulsen H
[Ad] Endereço:Institute of General Botany, Johannes-Gutenberg University Mainz , Johannes-von-Müller-Weg 6, 55128 Mainz, Germany.
[Ti] Título:Water-Soluble Chlorophyll Protein (WSCP) Stably Binds Two or Four Chlorophylls.
[So] Source:Biochemistry;56(12):1726-1736, 2017 Mar 28.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Water-soluble chlorophyll proteins (WSCPs) of class IIa from Brassicaceae form tetrameric complexes containing one chlorophyll (Chl) per apoprotein but no carotenoids. The complexes are remarkably stable toward dissociation and protein denaturation even at 100 °C and extreme pH values, and the Chls are partially protected against photooxidation. There are several hypotheses that explain the biological role of WSCPs, one of them proposing that they function as a scavenger of Chls set free upon plant senescence or pathogen attack. The biochemical properties of WSCP described in this paper are consistent with the protein acting as an efficient and flexible Chl scavenger. At limiting Chl concentrations, the recombinant WSCP apoprotein binds substoichiometric amounts of Chl (two Chls per tetramer) to form complexes that are as stable toward thermal dissociation, denaturation, and photodamage as the fully pigmented ones. If more Chl is added, these two-Chl complexes can bind another two Chls to reach the fully pigmented state. The protection of WSCP Chls against photodamage has been attributed to the apoprotein serving as a diffusion barrier for oxygen, preventing its access to triplet excited Chls and, thus, the formation of singlet oxygen. By contrast, the sequential binding of Chls by WSCP suggests a partially open or at least flexible structure, raising the question of how WSCP photoprotects its Chls without the help of carotenoids.
[Mh] Termos MeSH primário: Apoproteínas/química
Brassica/metabolismo
Clorofila/química
Complexos de Proteínas Captadores de Luz/química
Proteínas de Plantas/química
[Mh] Termos MeSH secundário: Apoproteínas/genética
Apoproteínas/metabolismo
Brassica/química
Brassica/genética
Clorofila/metabolismo
Expressão Gênica
Temperatura Alta
Concentração de Íons de Hidrogênio
Luz
Complexos de Proteínas Captadores de Luz/genética
Complexos de Proteínas Captadores de Luz/metabolismo
Modelos Moleculares
Oxirredução
Oxigênio
Ervilhas/química
Proteínas de Plantas/genética
Proteínas de Plantas/metabolismo
Ligação Proteica
Desnaturação Proteica
Domínios Proteicos
Multimerização Proteica
Estabilidade Proteica
Estrutura Secundária de Proteína
Proteínas Recombinantes de Fusão/química
Proteínas Recombinantes de Fusão/genética
Proteínas Recombinantes de Fusão/metabolismo
Oxigênio Singlete
Solubilidade
Tilacoides/química
Tilacoides/metabolismo
Água/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Apoproteins); 0 (Light-Harvesting Protein Complexes); 0 (Plant Proteins); 0 (Recombinant Fusion Proteins); 0 (WSCP protein, Brassica oleracea); 059QF0KO0R (Water); 1406-65-1 (Chlorophyll); 17778-80-2 (Singlet Oxygen); 5712ZB110R (chlorophyll b); S88TT14065 (Oxygen); YF5Q9EJC8Y (chlorophyll a)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170529
[Lr] Data última revisão:
170529
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170303
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.7b00075


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[PMID]:28237494
[Au] Autor:Bos I; Bland KM; Tian L; Croce R; Frankel LK; van Amerongen H; Bricker TM; Wientjes E
[Ad] Endereço:Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands.
[Ti] Título:Multiple LHCII antennae can transfer energy efficiently to a single Photosystem I.
[So] Source:Biochim Biophys Acta;1858(5):371-378, 2017 05.
[Is] ISSN:0006-3002
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Photosystems I and II (PSI and PSII) work in series to drive oxygenic photosynthesis. The two photosystems have different absorption spectra, therefore changes in light quality can lead to imbalanced excitation of the photosystems and a loss in photosynthetic efficiency. In a short-term adaptation response termed state transitions, excitation energy is directed to the light-limited photosystem. In higher plants a special pool of LHCII antennae, which can be associated with either PSI or PSII, participates in these state transitions. It is known that one LHCII antenna can associate with the PsaH site of PSI. However, membrane fractions were recently isolated in which multiple LHCII antennae appear to transfer energy to PSI. We have used time-resolved fluorescence-streak camera measurements to investigate the energy transfer rates and efficiency in these membrane fractions. Our data show that energy transfer from LHCII to PSI is relatively slow. Nevertheless, the trapping efficiency in supercomplexes of PSI with ~2.4 LHCIIs attached is 94%. The absorption cross section of PSI can thus be increased with ~65% without having significant loss in quantum efficiency. Comparison of the fluorescence dynamics of PSI-LHCII complexes, isolated in a detergent or located in their native membrane environment, indicates that the environment influences the excitation energy transfer rates in these complexes. This demonstrates the importance of studying membrane protein complexes in their natural environment.
[Mh] Termos MeSH primário: Complexos de Proteínas Captadores de Luz/metabolismo
Fotossíntese
Complexo de Proteína do Fotossistema I/metabolismo
Proteínas Quinases/metabolismo
Spinacia oleracea/metabolismo
Tilacoides/metabolismo
[Mh] Termos MeSH secundário: Transferência de Energia
Cinética
Complexos de Proteínas Captadores de Luz/química
Complexo de Proteína do Fotossistema I/química
Folhas de Planta/metabolismo
Proteínas Quinases/química
Espectrometria de Fluorescência
Espectrofotometria Ultravioleta
[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 (Light-Harvesting Protein Complexes); 0 (Photosystem I Protein Complex); 0 (photosystem I, psaH subunit); EC 2.7.- (Protein Kinases); EC 2.7.1.- (light-harvesting complex II kinase)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170824
[Lr] Data última revisão:
170824
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170227
[St] Status:MEDLINE



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