Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1433-0768
    Keywords: Key words Tungsten trioxides ; Tungsten trioxide hydrates ; Hydrogen intercalation ; X-ray powder diffraction ; Infrared spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrogen intercalation via spillover reaction in various tungsten trioxides leads to the formation of blue hydrogen bronzes. These reversible reactions induce changes in the W-O bond system while maintaining the W-O skeleton. The effect of the intercalation process on the host crystalline structure has been studied with respect to the ν(O-W-O) stretching vibration changes and lattice parameter variations by means of infrared and X-ray diffraction measurements. Among the main results, the intercalation process is shown to be strongly influenced by the structural type of the host compound as well as its amorphous versus crystalline nature. For instance, for the ReO3 type oxides (monoclinic and cubic WO3) and hexagonal WO3, ν(O-W-O) shifts to higher frequency are assigned to a shortening effect of W-O bonds. A W-O bond system arrangement is also measured for the crystallized and amorphous hydrates WO3 · H2O, but no detectable changes could be found in the pyrochlore WO3 and in the hydrate WO3·1/3 H2O.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2014-03-29
    Description: Bacterial type IV secretion systems translocate virulence factors into eukaryotic cells, distribute genetic material between bacteria and have shown potential as a tool for the genetic modification of human cells. Given the complex choreography of the substrate through the secretion apparatus, the molecular mechanism of the type IV secretion system has proved difficult to dissect in the absence of structural data for the entire machinery. Here we use electron microscopy to reconstruct the type IV secretion system encoded by the Escherichia coli R388 conjugative plasmid. We show that eight proteins assemble in an intricate stoichiometric relationship to form an approximately 3 megadalton nanomachine that spans the entire cell envelope. The structure comprises an outer membrane-associated core complex connected by a central stalk to a substantial inner membrane complex that is dominated by a battery of 12 VirB4 ATPase subunits organized as side-by-side hexameric barrels. Our results show a secretion system with markedly different architecture, and consequently mechanism, to other known bacterial secretion systems.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3998870/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3998870/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Low, Harry H -- Gubellini, Francesca -- Rivera-Calzada, Angel -- Braun, Nathalie -- Connery, Sarah -- Dujeancourt, Annick -- Lu, Fang -- Redzej, Adam -- Fronzes, Remi -- Orlova, Elena V -- Waksman, Gabriel -- 079605/Wellcome Trust/United Kingdom -- 098302/Wellcome Trust/United Kingdom -- MR/K012401/1/Medical Research Council/United Kingdom -- England -- Nature. 2014 Apr 24;508(7497):550-3. doi: 10.1038/nature13081. Epub 2014 Mar 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK [2] [3]. ; 1] Institut Pasteur, G5 Biologie structurale de la secretion bacterienne and UMR 3528-CNRS, 25 rue du Docteur Roux, 75015 Paris, France [2]. ; Institute of Structural and Molecular Biology, University College London and Birkbeck College, Malet Street, London WC1E 7HX, UK. ; Institut Pasteur, G5 Biologie structurale de la secretion bacterienne and UMR 3528-CNRS, 25 rue du Docteur Roux, 75015 Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24670658" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/chemistry/genetics/metabolism/ultrastructure ; *Bacterial Secretion Systems/genetics ; Cell Membrane/metabolism ; Escherichia coli/*chemistry/cytology/genetics/*ultrastructure ; Escherichia coli Proteins/chemistry/isolation & ; purification/metabolism/ultrastructure ; Microscopy, Electron ; Models, Molecular ; Multiprotein Complexes/chemistry/genetics/metabolism/ultrastructure
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    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
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...