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  • 1
    Publication Date: 2015-07-23
    Description: Bacteria share their ecological niches with other microbes. The bacterial type VI secretion system is one of the key players in microbial competition, as well as being an important virulence determinant during bacterial infections. It assembles a nano-crossbow-like structure in the cytoplasm of the attacker cell that propels an arrow made of a haemolysin co-regulated protein (Hcp) tube and a valine-glycine repeat protein G (VgrG) spike and punctures the prey's cell wall. The nano-crossbow is stably anchored to the cell envelope of the attacker by a membrane core complex. Here we show that this complex is assembled by the sequential addition of three type VI subunits (Tss)-TssJ, TssM and TssL-and present a structure of the fully assembled complex at 11.6 A resolution, determined by negative-stain electron microscopy. With overall C5 symmetry, this 1.7-megadalton complex comprises a large base in the cytoplasm. It extends in the periplasm via ten arches to form a double-ring structure containing the carboxy-terminal domain of TssM (TssMct) and TssJ that is anchored in the outer membrane. The crystal structure of the TssMct-TssJ complex coupled to whole-cell accessibility studies suggest that large conformational changes induce transient pore formation in the outer membrane, allowing passage of the attacking Hcp tube/VgrG spike.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Durand, Eric -- Nguyen, Van Son -- Zoued, Abdelrahim -- Logger, Laureen -- Pehau-Arnaudet, Gerard -- Aschtgen, Marie-Stephanie -- Spinelli, Silvia -- Desmyter, Aline -- Bardiaux, Benjamin -- Dujeancourt, Annick -- Roussel, Alain -- Cambillau, Christian -- Cascales, Eric -- Fronzes, Remi -- England -- Nature. 2015 Jul 30;523(7562):555-60. doi: 10.1038/nature14667. Epub 2015 Jul 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Laboratoire d'Ingenierie des Systemes Macromoleculaires, Aix-Marseille Universite - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France [2] Architecture et Fonction des Macromolecules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [3] G5 Biologie structurale de la secretion bacterienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [4] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [5] AFMB, Aix-Marseille Universite, IHU Mediterranee Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France. ; 1] Architecture et Fonction des Macromolecules Biologiques, CNRS, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France [2] AFMB, Aix-Marseille Universite, IHU Mediterranee Infection, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France. ; Laboratoire d'Ingenierie des Systemes Macromoleculaires, Aix-Marseille Universite - CNRS, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. ; UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France. ; 1] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [2] Unite de Bioinformatique Structurale, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France. ; 1] G5 Biologie structurale de la secretion bacterienne, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France [2] UMR 3528, CNRS, Institut Pasteur, 25-28 rue du Docteur Roux, 75015 Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26200339" target="_blank"〉PubMed〈/a〉
    Keywords: *Bacterial Secretion Systems ; Cell Membrane/chemistry/metabolism ; Crystallography, X-Ray ; Cytoplasm/chemistry/metabolism ; Escherichia coli/*chemistry/metabolism ; Escherichia coli Proteins/biosynthesis/*chemistry ; Lipopeptides/biosynthesis/*chemistry ; Membrane Proteins/biosynthesis/*chemistry ; Microscopy, Electron ; Models, Molecular ; Multiprotein Complexes/*biosynthesis/*chemistry ; Periplasm/chemistry/metabolism ; Porosity ; Protein Structure, Tertiary ; Protein Subunits/biosynthesis/chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 1984-07-15
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 3
    Publication Date: 2012-12-07
    Description: In an attempt to atomically assess interface and oxide-related point defects, a first basic multifrequency low-temperature electron spin resonance study has been carried out on semi-insulating (Fe compensated) GaAs/oxide structures, implying both powders and (100)GaAs/oxide slices, thermally grown in the range T ox =350–615 °C. Various spectra are observed: As for powders, this includes the 4-line EL2 defect spectrum centered at g~2.043 and characterized by the isotropic hyperfine constant A iso ~ 910 G, ascribed to the 75 As Ga + antisite defect. Observed in freshly crushed powder, it substantially increases in density with oxidation, in line with theoretical expectation; A maximum appears reached for at T ox ~440 °C. It is not observed in the parent c-GaAs wafer. A second isotropic signal is observed at g~1.937 in powders for T ox in the range 510–615 °C, but only after additional VUV irradiation; it may corres...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 4
    Publication Date: 2016-10-08
    Description: Anthocyanins are a group of colorful and bioactive natural pigments with important physiological and ecological functions in plants. We found an MYB transcription factor (PtrMYB119) from Populus trichocarpa that positively regulates anthocyanin production when expressed under the control of the CaMV 35S promoter in transgenic Arabidopsis . Amino acid sequence analysis revealed that PtrMYB119 is highly homologous to Arabidopsis PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), a well-known transcriptional activator of anthocyanin biosynthesis. Independently produced transgenic poplars overexpressing PtrMYB119 or PtrMYB120 (a paralogous gene to PtrMYB119 ) (i.e., 35S::PtrMYB119 and 35S::PtrMYB120, respectively) showed elevated accumulation of anthocyanins in the whole plants, including leaf, stem and even root tissues. Using a reverse-phase high-performance liquid chromatography, we confirmed that the majority of the accumulated anthocyanin in our transgenic poplar is cyanidin-3- O -glucoside. Gene expression analyses revealed that most of the genes involved in the anthocyanin biosynthetic pathway were highly upregulated in 35S::PtrMYB119 poplars compared with the nontransformed control poplar. Among these genes, expression of PtrCHS1 ( Chalcone Synthase1 ) and PtrANS2 ( Anthocyanin Synthase2 ), which catalyze the initial and last steps of anthocyanin biosynthesis, respectively, was upregulated by up to 350-fold. Subsequent transient activation assays confirmed that PtrMYB119 activated the transcription of both PtrCHS1 and PtrANS2 . Interestingly, expression of MYB182 , a repressor of both anthocyanin and proanthocyanidin (PA) biosynthesis, was largely suppressed in 35S::PtrMYB119 poplars, while expression of MYB134 , an activator of PA biosynthesis, was not changed significantly. More interestingly, high-level accumulation of anthocyanins in 35S::PtrMYB119 poplars did not have an adverse effect on plant growth. Taken together, our results demonstrate that PtrMYB119 and PtrMYB120 function as transcriptional activators of anthocyanin accumulation in both Arabidopsis and poplar.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
    Publication Date: 2014-12-06
    Print ISSN: 0947-8396
    Electronic ISSN: 1432-0630
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 6
    Publication Date: 2015-09-02
    Print ISSN: 0032-079X
    Electronic ISSN: 1573-5036
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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