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Pesquisa : B03.280.750 [Categoria DeCS]
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  1 / 1682 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 / 1682 MEDLINE  
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[PMID]:29318299
[Au] Autor:Jutersek M; Klemencic M; Dolinar M
[Ti] Título:Discrimination Between Synechocystis Members (Cyanobacteria) Based on Heterogeneity of Their 16S rRNA and ITS Regions.
[So] Source:Acta Chim Slov;64(4):804-817, 2017 Dec.
[Is] ISSN:1318-0207
[Cp] País de publicação:Slovenia
[La] Idioma:eng
[Ab] Resumo:Cyanobacteria are an important group of microorganisms displaying a range of morphologies that enable phenotypic differentiation between the major lineages of cyanobacteria, often to the genus level, but rarely to species or strain level. We focused on the unicellular genus Synechocystis that includes the model cyanobacterial strain PCC 6803. For 11 Synechocystis members obtained from cell culture collections, we sequenced the variable part of the 16S rRNA-encoding region and the 16S - 23S internally transcribed spacer (ITS), both standardly used in taxonomy. In combination with microscopic examination we observed that 2 out of 11 strains from cell culture collections were clearly different from typical Synechocystis members. For the rest of the samples, we demonstrated that both sequenced genomic regions are useful for discrimination between investigated species and that the ITS region alone allows for a reliable differentiation between Synechocystis strains.
[Mh] Termos MeSH primário: RNA Ribossômico 16S/química
Synechocystis/genética
[Mh] Termos MeSH secundário: Clonagem Molecular
DNA Espaçador Ribossômico/química
Análise de Sequência de RNA
Synechocystis/classificação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (DNA, Ribosomal Spacer); 0 (RNA, Ribosomal, 16S)
[Em] Mês de entrada:1803
[Cu] Atualização por classe:180306
[Lr] Data última revisão:
180306
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180111
[St] Status:MEDLINE


  3 / 1682 MEDLINE  
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[PMID]:29281679
[Au] Autor:Loeschcke A; Dienst D; Wewer V; Hage-Hülsmann J; Dietsch M; Kranz-Finger S; Hüren V; Metzger S; Urlacher VB; Gigolashvili T; Kopriva S; Axmann IM; Drepper T; Jaeger KE
[Ad] Endereço:Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany.
[Ti] Título:The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis.
[So] Source:PLoS One;12(12):e0189816, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge. We thus explored the suitability of the metabolically versatile photosynthetic α-proteobacterium Rhodobacter capsulatus SB1003 and cyanobacterium Synechocystis sp. PCC 6803 as alternative hosts for biosynthesis of cyclic plant triterpenes. Therefore, 2,3-oxidosqualene production was implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase), LUP1 (lupeol synthase), THAS1 (thalianol synthase) and MRN1 (marneral synthase) derived from model plant Arabidopsis thaliana. While successful accumulation of 2,3-oxidosqualene could be detected by LC-MS analysis in both hosts, cyclase expression resulted in differential production profiles. CAS1 catalyzed conversion to only cycloartenol, but expression of LUP1 yielded lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression did not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol was observed in Synechocystis but not in R. capsulatus. Our findings thus indicate that 2,3-oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties. Therefore, photosynthetic α-proteo- and cyanobacteria are promising alternative candidates for providing new bacterial access to the broad class of triterpenes for biotechnological applications.
[Mh] Termos MeSH primário: Rhodobacter capsulatus/metabolismo
Synechocystis/metabolismo
Triterpenos/metabolismo
[Mh] Termos MeSH secundário: Ciclização
Regulação Bacteriana da Expressão Gênica
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Triterpenes)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180129
[Lr] Data última revisão:
180129
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171228
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0189816


  4 / 1682 MEDLINE  
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[PMID]:28745633
[Au] Autor:De Porcellinis A; Frigaard NU; Sakuragi Y
[Ad] Endereço:Carlsberg Research Laboratory.
[Ti] Título:Determination of the Glycogen Content in Cyanobacteria.
[So] Source:J Vis Exp;(125), 2017 Jul 17.
[Is] ISSN:1940-087X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Cyanobacteria accumulate glycogen as a major intracellular carbon and energy storage during photosynthesis. Recent developments in research have highlighted complex mechanisms of glycogen metabolism, including the diel cycle of biosynthesis and catabolism, redox regulation, and the involvement of non-coding RNA. At the same time, efforts are being made to redirect carbon from glycogen to desirable products in genetically engineered cyanobacteria to enhance product yields. Several methods are used to determine the glycogen contents in cyanobacteria, with variable accuracies and technical complexities. Here, we provide a detailed protocol for the reliable determination of the glycogen content in cyanobacteria that can be performed in a standard life science laboratory. The protocol entails the selective precipitation of glycogen from the cell lysate and the enzymatic depolymerization of glycogen to generate glucose monomers, which are detected by a glucose oxidase-peroxidase (GOD-POD) enzyme coupled assay. The method has been applied to Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7002, two model cyanobacterial species that are widely used in metabolic engineering. Moreover, the method successfully showed differences in the glycogen contents between the wildtype and mutants defective in regulatory elements or glycogen biosynthetic genes.
[Mh] Termos MeSH primário: Ensaios Enzimáticos/métodos
Glicogênio/metabolismo
Synechocystis/metabolismo
[Mh] Termos MeSH secundário: Glucose/análise
Glucose/metabolismo
Glucose Oxidase/metabolismo
Manitol/metabolismo
Peroxidase/metabolismo
Synechocystis/genética
Gravação em Vídeo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
3OWL53L36A (Mannitol); 9005-79-2 (Glycogen); EC 1.1.3.4 (Glucose Oxidase); EC 1.11.1.7 (Peroxidase); IY9XDZ35W2 (Glucose)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180130
[Lr] Data última revisão:
180130
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170727
[St] Status:MEDLINE
[do] DOI:10.3791/56068


  5 / 1682 MEDLINE  
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[PMID]:29216280
[Au] Autor:Zavrel T; Ocenásová P; Cervený J
[Ad] Endereço:Department of Adaptive Biotechnologies, Global Change Research Institute CAS, Brno, Czech Republic.
[Ti] Título:Phenotypic characterization of Synechocystis sp. PCC 6803 substrains reveals differences in sensitivity to abiotic stress.
[So] Source:PLoS One;12(12):e0189130, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Synechocystis sp. PCC 6803 is a widely used model cyanobacterium, whose substrains can vary on both genotype and phenotype levels. Previously described phenotypic variations include ability of mixotrophic growth, ability of movement on agar plates and variations in pigments composition or cell size. In this study, we report for the first time significant variation among Synechocystis substrains in complex cellular traits such as growth rate, photosynthesis efficiency, cellular dry weight and cellular composition (including protein or carbohydrates content). We also confirmed previously reported differences in cell size. Synechocystis cultures were cultivated in controlled environment of flat panel photobioreactors under red, blue and white light of intensities up to 790 µmol(photons) m-2 s-1, temperatures 23°C-60°C, input CO2 concentrations ranging from 400 to 15 000 ppm and in BG11 cultivation medium with and without addition of NaCl. Three Synechocystis substrains were used for the comparative experiments: GT-L, GT-B (Brno, CZ) and PCC-B (Brno, CZ). Growth rates of Synechocystis GT-B were inhibited under high intensities of red light (585-670 nm), and growth rates of both substrains GT-B and PCC-B were inhibited under photons of wavelengths 485-585 nm and 670-700 nm. Synechocystis GT-B was more sensitive to low temperatures than the other two tested substrains, and Synechocystis GT-L was sensitive to the presence of NaCl in the cultivation media. The results suggest that stress sensitivity of commonly used Synechocystis substrains can strongly vary, similarly as glucose tolerance or motility as reported previously. Our study further supports the previous statement that emphasizes importance of proper Synechocystis substrains selection and awareness of phenotypical differences among Synechocystis substrains which is crucial for comparative and reproducible research. This is highly relevant for studies related to stress physiology and development of sustainable biotechnological applications.
[Mh] Termos MeSH primário: Estresse Fisiológico
Synechocystis/fisiologia
[Mh] Termos MeSH secundário: Fenótipo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[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:171208
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0189130


  6 / 1682 MEDLINE  
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[PMID]:29023570
[Au] Autor:Sato N; Kamimura R; Kaneta K; Yoshikawa M; Tsuzuki M
[Ad] Endereço:School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
[Ti] Título:Species-specific roles of sulfolipid metabolism in acclimation of photosynthetic microbes to sulfur-starvation stress.
[So] Source:PLoS One;12(10):e0186154, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Photosynthetic organisms utilize sulfate for the synthesis of sulfur-compounds including proteins and a sulfolipid, sulfoquinovosyl diacylglycerol. Upon ambient deficiency in sulfate, cells of a green alga, Chlamydomonas reinhardtii, degrade the chloroplast membrane sulfolipid to ensure an intracellular-sulfur source for necessary protein synthesis. Here, the effects of sulfate-starvation on the sulfolipid stability were investigated in another green alga, Chlorella kessleri, and two cyanobacteria, Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. The results showed that sulfolipid degradation was induced only in C. kessleri, raising the possibility that this degradation ability was obtained not by cyanobacteria, but by eukaryotic algae during the evolution of photosynthetic organisms. Meanwhile, Synechococcus disruptants concerning sqdB and sqdX genes, which are involved in successive reactions in the sulfolipid synthesis pathway, were respectively characterized in cellular response to sulfate-starvation. Phycobilisome degradation intrinsic to Synechococcus, but not to Synechocystis, and cell growth under sulfate-starved conditions were repressed in the sqdB and sqdX disruptants, respectively, relative to in the wild type. Their distinct phenotypes, despite the common loss of the sulfolipid, inferred specific roles of sqdB and sqdX. This study demonstrated that sulfolipid metabolism might have been developed to enable species- or cyanobacterial-strain dependent processes for acclimation to sulfate-starvation.
[Mh] Termos MeSH primário: Chlorella/crescimento & desenvolvimento
Glicolipídeos/metabolismo
Enxofre/metabolismo
Synechococcus/crescimento & desenvolvimento
Synechocystis/crescimento & desenvolvimento
[Mh] Termos MeSH secundário: Aclimatação
Proteínas de Algas/genética
Proteínas de Bactérias/genética
Chlorella/genética
Chlorella/metabolismo
Evolução Molecular
Fotossíntese
Especificidade da Espécie
Estresse Fisiológico
Synechococcus/genética
Synechococcus/metabolismo
Synechocystis/genética
Synechocystis/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Algal Proteins); 0 (Bacterial Proteins); 0 (Glycolipids); 0 (sulfoquinovosyl diglyceride); 70FD1KFU70 (Sulfur)
[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:171013
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0186154


  7 / 1682 MEDLINE  
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[PMID]:28934279
[Au] Autor:Garcia-Alles LF; Lesniewska E; Root K; Aubry N; Pocholle N; Mendoza CI; Bourillot E; Barylyuk K; Pompon D; Zenobi R; Reguera D; Truan G
[Ad] Endereço:LISBP, CNRS, INRA, INSA, University of Toulouse, Toulouse, France.
[Ti] Título:Spontaneous non-canonical assembly of CcmK hexameric components from ß-carboxysome shells of cyanobacteria.
[So] Source:PLoS One;12(9):e0185109, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:CcmK proteins are major constituents of icosahedral shells of ß-carboxysomes, a bacterial microcompartment that plays a key role for CO2 fixation in nature. Supported by the characterization of bidimensional (2D) layers of packed CcmK hexamers in crystal and electron microscopy structures, CcmK are assumed to be the major components of icosahedral flat facets. Here, we reassessed the validity of this model by studying CcmK isoforms from Synechocystis sp. PCC6803. Native mass spectrometry studies confirmed that CcmK are hexamers in solution. Interestingly, potential pre-assembled intermediates were also detected with CcmK2. Atomic-force microscopy (AFM) imaging under quasi-physiological conditions confirmed the formation of canonical flat sheets with CcmK4. Conversely, CcmK2 formed both canonical and striped-patterned patches, while CcmK1 assembled into remarkable supra-hexameric curved honeycomb-like mosaics. Mutational studies ascribed the propensity of CcmK1 to form round assemblies to a combination of two features shared by at least one CcmK isoform in most ß-cyanobacteria: a displacement of an α helical portion towards the hexamer edge, where a potential phosphate binding funnel forms between packed hexamers, and the presence of a short C-terminal extension in CcmK1. All-atom molecular dynamics supported a contribution of phosphate molecules sandwiched between hexamers to bend CcmK1 assemblies. Formation of supra-hexameric curved structures could be reproduced in coarse-grained simulations, provided that adhesion forces to the support were weak. Apart from uncovering unprecedented CcmK self-assembly features, our data suggest the possibility that transitions between curved and flat assemblies, following cargo maturation, could be important for the biogenesis of ß-carboxysomes, possibly also of other BMC.
[Mh] Termos MeSH primário: Proteínas de Bactérias/metabolismo
[Mh] Termos MeSH secundário: Silicatos de Alumínio/química
Proteínas de Bactérias/química
Proteínas de Bactérias/genética
Cromatografia em Gel
Isomerismo
Espectrometria de Massas
Microscopia de Força Atômica
Simulação de Dinâmica Molecular
Mutação
Fosfatos/química
Multimerização Proteica
Estrutura Quaternária de Proteína
Estrutura Secundária de Proteína
Soluções
Solventes/química
Synechocystis
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Aluminum Silicates); 0 (Bacterial Proteins); 0 (CcmK protein, Synechocystis sp.); 0 (Phosphates); 0 (Solutions); 0 (Solvents); V8A1AW0880 (mica)
[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:170922
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0185109


  8 / 1682 MEDLINE  
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[PMID]:28734838
[Au] Autor:Wang X; Lei G; Wu X; Wang F; Lai C; Li Z
[Ad] Endereço:College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, Jiangxi, 330045, China.
[Ti] Título:Expression, purification and characterization of sll1981 protein from cyanobacterium Synechocystis sp. PCC6803.
[So] Source:Protein Expr Purif;139:21-28, 2017 Nov.
[Is] ISSN:1096-0279
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The sll1981 protein from cyanobacterium Synechocystis sp. PCC6803 had been reported to exhibit acetolactate synthase (ALS) and L-myo-inositol-1-phosphate synthase (MIPS) activities previously. Based on amino acids sequences alignment, sll1981 protein was postulated to function as α-ketoglutarate decarboxylase (α-KGD), which played important role in completing cyanobacterial tricarboxylic acid (TCA) cycle. However the detailed enzymatic kinetics of sll1981 as ALS, MIPS and α-KGD were not determined yet. In this study, the recombinant sll1981 protein was purified from supernatant of E. coli cell and the substrate specificity of sll1981 towards pyruvate, d-glucose-6-phosphate and α-ketoglutarate was examined using homogenous recombinant sll1981. Steady-state kinetics results showed that sll1981 was a dual functional enzyme, which displayed much higher activity as α-KGD than as ALS. At the same time the MIPS activity of sll1981 was not detectable, although it was reported to be as MIPS previously. These findings not only confirmed the previous statement of the function of sll1981 as ALS and disputed the claimed function of sll1981 as MIPS, but also affirmed the new function of sll1981 as α-KGD. Therefore sll1981 was probably a key enzyme in completing the TCA cycle of Synechocystis sp. PCC6803.
[Mh] Termos MeSH primário: Acetolactato Sintase/metabolismo
Proteínas de Bactérias/metabolismo
Proteínas Recombinantes/metabolismo
Synechocystis/enzimologia
[Mh] Termos MeSH secundário: Acetolactato Sintase/química
Acetolactato Sintase/genética
Acetolactato Sintase/isolamento & purificação
Proteínas de Bactérias/química
Proteínas de Bactérias/genética
Proteínas de Bactérias/isolamento & purificação
Clonagem Molecular
Proteínas Recombinantes/química
Proteínas Recombinantes/genética
Proteínas Recombinantes/isolamento & purificação
Especificidade por Substrato
Synechocystis/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Recombinant Proteins); EC 2.2.1.6 (Acetolactate Synthase)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170920
[Lr] Data última revisão:
170920
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170724
[St] Status:MEDLINE


  9 / 1682 MEDLINE  
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[PMID]:28696278
[Au] Autor:Kowata H; Tochigi S; Takahashi H; Kojima S
[Ad] Endereço:Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
[Ti] Título:Outer Membrane Permeability of Cyanobacterium Synechocystis sp. Strain PCC 6803: Studies of Passive Diffusion of Small Organic Nutrients Reveal the Absence of Classical Porins and Intrinsically Low Permeability.
[So] Source:J Bacteriol;199(19), 2017 Oct 01.
[Is] ISSN:1098-5530
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The outer membrane of heterotrophic Gram-negative bacteria plays the role of a selective permeability barrier that prevents the influx of toxic compounds while allowing the nonspecific passage of small hydrophilic nutrients through porin channels. Compared with heterotrophic Gram-negative bacteria, the outer membrane properties of cyanobacteria, which are Gram-negative photoautotrophs, are not clearly understood. In this study, using small carbohydrates, amino acids, and inorganic ions as permeation probes, we determined the outer membrane permeability of sp. strain PCC 6803 in intact cells and in proteoliposomes reconstituted with outer membrane proteins. The permeability of this cyanobacterium was >20-fold lower than that of The predominant outer membrane proteins Slr1841, Slr1908, and Slr0042 were not permeable to organic nutrients and allowed only the passage of inorganic ions. Only the less abundant outer membrane protein Slr1270, a homolog of the export channel TolC, was permeable to organic solutes. The activity of Slr1270 as a channel was verified in a recombinant Slr1270-producing outer membrane. The lack of putative porins and the low outer membrane permeability appear to suit the cyanobacterial autotrophic lifestyle; the highly impermeable outer membrane would be advantageous to cellular survival by protecting the cell from toxic compounds, especially when the cellular physiology is not dependent on the uptake of organic nutrients. Because the outer membrane of Gram-negative bacteria affects the flux rates for various substances into and out of the cell, its permeability is closely associated with cellular physiology. The outer membrane properties of cyanobacteria, which are photoautotrophic Gram-negative bacteria, are not clearly understood. Here, we examined the outer membrane of sp. strain PCC 6803. We revealed that it is relatively permeable to inorganic ions but is markedly less permeable to organic nutrients, with >20-fold lower permeability than the outer membrane of Such permeability appears to fit the cyanobacterial lifestyle, in which the diffusion pathway for inorganic solutes may suffice to sustain the autotrophic physiology, illustrating a link between outer membrane permeability and the cellular lifestyle.
[Mh] Termos MeSH primário: Proteínas da Membrana Bacteriana Externa/metabolismo
Permeabilidade da Membrana Celular
Compostos Orgânicos/química
Porinas/metabolismo
Synechocystis/fisiologia
[Mh] Termos MeSH secundário: Proteínas da Membrana Bacteriana Externa/química
Proteínas da Membrana Bacteriana Externa/isolamento & purificação
Difusão
Proteolipídeos/química
Proteolipídeos/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Outer Membrane Proteins); 0 (Organic Chemicals); 0 (Porins); 0 (Proteolipids); 0 (proteoliposomes)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171003
[Lr] Data última revisão:
171003
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170712
[St] Status:MEDLINE


  10 / 1682 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



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