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  • 1
    Electronic Resource
    Electronic Resource
    Site-directed mutagenesis of intimin α modulates intimin-mediated tissue tropism and host specificity (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 40 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The hallmark of enteropathogenic (EPEC) and enterohaemorrhagic (EHEC) Escherchia coli adhesion to host cells is intimate attachment leading to the formation of distinctive ‘attaching and effacing’ lesions. This event is mediated, in part, by binding of the bacterial adhesion molecule intimin to a second bacterial protein, Tir, delivered by a type III secretion system into the host cell plasma membrane. The receptor-binding activity of intimin is localized to the C-terminal 280 amino acids (Int280) and at least five distinct intimin types (α, β, γ, δ and ε) have been identified thus far. In addition to binding to Tir, intimin can also bind to a component encoded by the host. The consequence of latter intimin-binding activity may determine tissue tropism and host specificity. In this study we selected three amino acids in intimin, which are implicated in Tir binding, for site-directed mutagenesis. We used the yeast two-hybrid system and gel overlays to study intimin–Tir protein interaction. In addition, the biological consequences of the mutagenesis was tested using a number of infection models (cultured epithelial cells, human intestinal explants and a mouse model). We report that while an I237/897A substitution (positions numbered according to Int280α/whole intimin α) in intimin α did not have any affect on its biological activity, a T255/914A substitution attenuated intimin activity in vivo. In contrast, the mutation V252/911A affected tissue targeting in the human intestinal explant model and attenuated the biological activity of intimin in the mouse model. This study provides the first clues of the molecular basis of how intimin mediates tissue tropism and host specificity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02371.x
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  • 2
    Electronic Resource
    Electronic Resource
    Activation of enteropathogenic Escherichia coli (EPEC) LEE2 and LEE3 operons by Ler (2000)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 38 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Enteropathogenic Escherichia coli (EPEC) produces attaching and effacing lesions (AE) on epithelial cells. The genes involved in the formation of the AE lesions are contained within a pathogenicity island named the locus of enterocyte effacement (LEE). The LEE comprises 41 open reading frames organized in five major operons: LEE1, LEE2, LEE3, LEE4 and tir. The first gene of the LEE1 operon encodes a transcription activator of the other LEE operons that is called the LEE-encoded regulator (Ler). The LEE2 and LEE3 operons are divergently transcribed with overlapping −10 promoter regions, and gene fusion studies have shown that they are both activated by Ler. Deletion analysis, using lacZ reporter fusions, of the LEE2 and LEE3 promoters demonstrated that deletions extending closer to the LEE2 transcription start site than −247 bp lead to loss of activation by Ler, whereas only 70 bp upstream of the LEE3 transcription start site is required for Ler-mediated activation. We have purified Ler as a His-tagged protein and used it to perform DNA-binding assays with LEE2 and LEE3. We observed that Ler bound to a DNA fragment containing the −300 to +1 region of LEE2; however, it failed to bind to a DNA fragment containing the −300 to +1 region of LEE3, suggesting that Ler activates both operons by only binding to the regulatory region upstream of LEE2. The Ler-activatable LEE3::lacZ fusions extended to what would be −246 bp of the LEE2 operon. A lacZ fusion from the −300 to +1 region of LEE3 failed to be activated by Ler, consistent with our hypothesis that Ler activates the expression of LEE2 and LEE3 by binding to a region located downstream of the LEE3 transcription start site. DNase I footprinting revealed that Ler protected a region of 121 bp upstream of LEE2. Purified Ler mutated in the coiled-coil domain was unable to activate transcription and to bind to the LEE2 regulatory region. These data indicate that Ler may bind as a multimer to LEE2 and activate both divergent operons by a novel mechanism potentially involving changes in the DNA structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02168.x
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  • 3
    Electronic Resource
    Electronic Resource
    Coiled-coil proteins associated with type III secretion systems: a versatile domain revisited (2002)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 45 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Summary The pathogenic potential of many Gram-negative bacteria is indicated by the possession of a specialized type III secretion system that is used to deliver virulence effector proteins directly into the cellular environment of the eukaryotic host. Extracellular assemblies of secreted proteins contrive a physical link between the pathogen and host cytosol and enable the translocated effectors to bypass the bacterial and host membranes in a single step. Subsequent interactions of some effector proteins with host cytoskeletal and signalling proteins result in modulation of the cytoskeletal architecture of the aggressed cell and facilitate entry, survival and dissemination of the pathogen. Although the secreted components of type III secretion systems are diverse, many are predicted to share a common coiled-coil structural feature. Coiled-coils are ubiquitous and highly versatile assembly motifs found in a wide range of structural and regulatory proteins. The prevalence of these domains in secreted virulence effector proteins suggests a fundamental contribution to multiple aspects of their function, and evidence accumulating from functional studies suggests an intrinsic involvement of coiled-coils in subunit assembly, translocation and flexible interactions with multiple bacterial and host proteins. The known functional flexibility that coiled-coil domains confer upon proteins provides insights into some of the pathogenic mechanisms used during interaction with the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03083.x
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  • 4
    Electronic Resource
    Electronic Resource
    The surface hydroxyl population in bone mineral (1968)
    Springer
    Colloid & polymer science 222 (1968), S. 56-61 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Zur Bestimmung der Oberflächen-OH-Gruppen im Knochenmineral, welches als unreiner Hydroxyl-apatit beschrieben werden kann, wurde Lithium-Aluminiumhydrid in Diglymelösung verwendet. Die Menge der OH-Gruppen wurde aus der entwickelten Wasserstoffmenge berechnet. Ein Vergleich der auf diesem Wege ermittelten Menge an OH-Gruppen mit der aus der spezifischen Oberfläche (BET N2-Adsorption) und der Kristallstruktur errechneten zeigt ein Defizit von mehr als 50%. Zur Deutung werden mehrere Möglichkeiten diskutiert. Die Annahme, daß echte Fehlstellen für die Oberflächen-OH-Gruppen vorliegen, wird bevorzugt.
    Notes: Summary Lithium aluminium hydride reagent has been employed in the determination of surface OH groups in bone mineral which may be described as an impure hydroxyapatite. The dehydrated sample is dropped into a diglyme solution of LiAlH4 and hydrogen gas evolution is measured. One mole of hydrogen is evolved by each mole of OH groups. The total surface is previously measured by the B.E.T. nitrogen adsorption method. Thus it is possible to compare the number of surface OH groups found per unit area with that estimated on the basis of the known crystal lattice. Less than fifty percent of the estimated number is found. Several possible explanations for the apparent discrepancy are offered. Perhaps the most compelling one is the suggestion of an actual deficiency of surface hydroxyl groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01507367
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  • 5
    Electronic Resource
    Electronic Resource
    Increased T-type Ca2+ channel activity as a determinant of cellular toxicity in neuronal cell lines expressing polyglutamine-expanded human androgen receptors (2000)
    Springer
    Molecular and cellular biochemistry 203 (2000), S. 23-31 
    Details
    ISSN: 1573-4919
    Keywords: T-type Ca2+ channel ; polyglutamine-expanded androgen receptor ; CAG trinucleotide repeats ; spinobulbar muscular atrophy ; apoptosis ; motorneuron ; cell lines ; neuroblastoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We have analyzed Ca2+ currents in two neuroblastoma-motor neuron hybrid cell lines that expressed normal or glutamine-expanded human androgen receptors (polyGln-expanded AR) either transiently or stably. The cell lines express a unique, low-threshold, transient type of Ca2+ current that is not affected by L-type Ca2+ channel blocker (PN 200-110), N-type Ca2+ channel blocker (ω-conotoxin GVIA) or P-type Ca2+ channel blocker (Agatoxin IVA) but is blocked by either Cd2+ or Ni2+. This pharmacological profile most closely resembles that of T-type Ca2+ channels [1-3]. Exposure to androgen had no effect on control cell lines or cells transfected with normal AR but significantly changed the steady-state activation in cells transfected with expanded AR. The observed negative shift in steady-state activation results in a large increase in the T-type Ca2+ channel window current. We suggest that Ca2+ overload due to abnormal voltage-dependence of transient Ca2+ channel activation may contribute to motor neuron toxicity in spinobulbar muscular atrophy (SBMA). This hypothesis is supported by the additional finding that, at concentrations that selectively block T-type Ca2+ channel currents, Ni2+ significantly reduced cell death in cell lines transfected with polyGln-expanded AR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007010020228
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  • 6
    Electronic Resource
    Electronic Resource
    Timing of callase activity and cytoplasmic male sterility in Petunia (1969)
    Springer
    Biochemical genetics 3 (1969), S. 451-455 
    Details
    ISSN: 1573-4927
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A study of callase activity in relation to cytogenetical expressions in cytoplasmic male sterile and male fertile Petunia indicated differential timing of the localized enzyme activity. Enzyme activity was determined by a new test. The possible relations between the mode of action of the extrachromosomal gene, timing of the enzyme activity, and male sterility are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00485605
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  • 7
    Electronic Resource
    Electronic Resource
    Conference on automation of glass furnaces (1965)
    Springer
    Glass and ceramics 22 (1965), S. 356-356 
    Details
    ISSN: 1573-8515
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678060
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  • 8
    Electronic Resource
    Electronic Resource
    Practical aspects, and the use of male sterility in the production of hybrid tomato seed (1967)
    Springer
    Euphytica 16 (1967), S. 300-310 
    Details
    ISSN: 1573-5060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Hybrid seed production steps are evaluated and the pertinent literature reviewed. Experimental data are presented of environmental effects on pollination efficiency, pollen germination, and speed of pollen tube growth. A comparison between the use of male sterile and male fertile ovule parents bears out the superior efficiency of the former in hybrid seed production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043465
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  • 9
    Electronic Resource
    Electronic Resource
    Funktionelle Derivate von Polynitroverbindungen (1968)
    Springer
    Monatshefte für Chemie 99 (1968), S. 1336-1350 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract The study of reaction products from 2-nitro-3-acetoxy-1-propene1 byMichael reactions led to the preparation of new aliphatic polynitro compounds containing functional groups. Of particular interest are compounds containing threegem-dinitro groups in a chain that have been obtained by direct nitration of theaci-salts of the condensation products from 2-nitro-3-acetoxy-1-propene withgem-dinitrocompounds. The reaction conditions have been established and the structure of the new compounds elucidated.
    Notes: Zusammenfassung DieMichael-Kondensation des 2-Nitro-3-acetoxy-1-propens1 ermöglichte die Darstellung neuer aliphatischer Polynitroverbindungen mit zusätzlichen funktionellen Gruppen. Von besonderem Interesse sind die Verbindungen mit dreigem-Dinitrogruppen in der Kette, die durch direkte Nitrierung derAci-Salze von Kondensationsprodukten des 2-Nitro-3-acetoxy-1-propens mitgem-Dinitroverbindungen erhalten wurden. Die Reaktionsbedingungen wurden ermittelt und die Struktur der neuen Verbindungen sichergestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902677
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  • 10
    Electronic Resource
    Electronic Resource
    A new spontaneous mouse mutation in the Kcne1 gene (2000)
    Springer
    Mammalian genome 11 (2000), S. 831-835 
    Details
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. A new mouse mutant, punk rocker (allele symbol Kcne1 pkr ), arose spontaneously on a C57BL/10J inbred strain background and is characterized by a distinctive head-tossing, circling, and ataxic phenotype. It is also profoundly and bilaterally deaf. The mutation resides in the Kcne1 gene on Chromosome (Chr) 16 and has been identified as a single base change within the coding region of the third exon. The C to T nucleotide substitution causes an arginine to be altered to a termination codon at amino acid position 67, and predictably this will result in a significantly truncated protein product. The Kcne1 pkr mutant represents the first spontaneous mouse model for the human disorder, Jervell and Lange-Nielsen syndrome, associated with mutations in the homologous KCNE1 gene on human Chr 21.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003350010178
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