Tübingen, Univ., Diss., 2007.

Hamburg, Univ., Diss., 2005. / Erscheinungsjahr an der Haupttitelstelle: 2004. Computerdatei im Fernzugriff.

Hamburg, Universiẗat, Diss., 2005. / Erscheinungsjahr an der Haupttitelstelle: 2004.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Ying Fang / Viral papain-like proteases (PLPs)-related proteins have been shown to be actively involved in host innate immunity manipulation and virus replication. In this dissertation, the research were focused on the elucidation of biological roles of nidoviral PLPs-related proteins in innate immunity suppression and viral RNA transcription regulation. Porcine Respiratory and Reproductive Syndrome Virus (PRRSV) is the most prominent swine diseases worldwide. Understanding PRRSV pathogenesis and development efficient vaccines are highly required in swine industry. PRRSV nsp2-related proteins including nsp2 and two ribosomal frameshifting products-nsp2TF and nsp2N share the same N-terminal PLP2 domain. In chapter 2, nsp2TF and nsp2N were demonstrated to be critical for host innate immunity suppression at least through the PLP2 domain-mediated deubiquitination and deISGylation effects. The infection of nsp2TF/nsp2N knockout mutants significantly upregulated antiviral innate immune responses in vitro. Furthermore, manipulating the expression of nsp2TF/nsp2N could enhance innate and adaptive immunity in pigs, providing potential basis for modified live vaccine development. In addition to the PLP2 domain of PRRSV nsp2-related proteins, the biological roles and biochemical nature of the poorly investigated long mysterious PLP2 downstream region was also characterized in Chapter 3. This long unknown region is also shared by nsp2-related proteins. At first, the hyper-phosphorylation nature of nsp2-related proteins was demonstrated. Physical features of this uncharacterized region was then delineated, including two intrinsically disordered hypervariable regions spaced by a structured inter-species conserved domain. One critical phosphorylated residues in the conserved domain were later proved to be of great importance in recombinant virus rescue and subgenomic RNAs accumulation. Collectively, our investigations underline the pleiotropic effects exerted by nsp2-related proteins in virus life cycle and potential contributions with pathogenesis. In Chapter 4, potential functions of PLP encoded by other nidovirus was also investigated. We discovered a unique cross-order recombination event, in which the chimeric picornavirus-enterovirus G expresses the PLP gene, homologous to torovirus (ToV) PLPs. Like other nidoviral PLPs, the recombinant ToV-PLP was proved to be a highly active deubiquinase/deISGylase and potent innate immune antagonist. After PLP knockout, viral fitness is significantly decreased and the suppression on host ubiquitination/ISGylation is largely reduced. Furthermore, host antiviral innate immune responses have been greatly upregulated post PLP knockout mutant infection. Our study underscores potential contributions of PLP domain in viral pathogenicity, and further provides an ideal example for how recombination shapes virus evolution. In summary, studies in this dissertation highlight the critical roles of nidoviral PLPs-related proteins in host immunity manipulation and virus replication, and more importantly, potential links with viral pathogenicity and application in vaccine development.

No description available.

No description available.

Les protéines de raisin thaumatin-like et chitinase sont d’un intérêt majeur, tant pour la recherche viticole de par leur implication dans les mécanismes de défense de la vigne, que pour la recherche en oenologie en raison de leur présence en quantité majoritaire dans le pool protéique d’un jus de raisin. La mise au point d’un protocole de quantification par chromatographie liquide et dosage immuno-enzymatique utilisant des gammes de protéines purifiées à partir de jus de raisin a permis de caractériser la diminution de la concentration de ces deux protéines au cours du procédé de vinification. Les propriétés tensioactives des deux protéines thaumatin-like et chitinase purifiées ont été évaluées, révélant que ni l’une ni l’autre ne pouvait à elle seule expliquer la formation et la stabilisation des bulles et de la mousse d’un Champagne. Une étude structurale de la protéine thaumatin-like VVTL1 a ensuite été menée dans l’optique de mieux comprendre les mécanismes chimiques, biologiques et physiques dans lesquels elle peut être impliquée. Une structure de VVTL1 a été modélisée par homologie et l’analyse de ses modes normaux a permis de révéler un mécanisme de type mâchoire autour d’une cavité acide, site potentiel de l’activité enzymatique de la protéine. Un feuillet beta en épingle à cheveux isolé dans la structure s’est révélé être très conservé et absolument spécifique à la superfamille des protéines thaumatin-like, ouvrant peut-être la voie vers l’élucidation complète du rôle biologique de ces protéines. Dans une seconde approche, la détermination de la structure d’un peptide sélectionné dans la séquence de VVTL1 par modélisation sous contraintes RMN a posé les bases d’une étude modèle de l’adsorption des protéines à la surface de la bentonite, argile utilisée pour la clarification des vins. / Grape proteins thaumatin-like and chitinase are of major interest, as much by the vine defense mechanisms they are involved in as by their dominance over the grape juice protein pool. Liquid chromatography and immunoassays allowed both proteins to be quantified in grape juice and Champagne, showing that their concentration decreases through winemaking. The involvement of these proteins in gas/liquid interfaces was also studied on the purified fractions from grape juice previously made for quantification standards. Results clearly indicated that neither thaumatin-like nor chitinase could alone explain bubble formation and foam stabilization in Champagne. A first study of the three-dimensional structure of the main thaumatin-like protein VVTL1 using homology molecular modeling was then achieved and normal modes analysis was performed on the VVTL1 model. It revealed a jaw-like mechanism opening and closing an acidic cleft assessed to be the enzymatic binding site. An isolated beta hairpin turned out to be highly conserved and specific to the thaumatin-like superfamilly. This domain could provide a first clue to unravel the mystery of the protein biological activity in the field of plant-pathogen interactions. A second approach was set up for the structure determination of a VVTL1 peptide using molecular modeling under NMR restraints. It could lead to a model study of protein adsorption on bentonite, a clay used for wine clarification.

Doctor of Philosophy / Department of Physics / Andrew G. Ivanov / A search is performed for heavy vector-like top quark partner (T) with electric charge +2/3 by using proton-proton collision events from Large Hadron Collider (LHC) at a centre- of-mass energy of 13 TeV. The data corresponds to an integrated luminosity of 35.9fb−1 collected by the Compact Muon Solenoid (CMS) experiment during 2016. The production of this new hypothetical particle is assumed to be in pairs and strong interaction is responsible for such production mechanism. T quarks can decay to various combinations of third generation quarks and standard model bosons: T → bW, tZ, or tH, and hence the final states consist of pair of opposite-sign leptons consistent with coming from a Z boson and jets. No significant excess has been observed and hence 95% CL upper limits are obtained on TT production cross section by assuming different branching ratios. T quark mass values below 1280 GeV are excluded in case of 100% branching fraction for T → tZ.

No description available.

No description available.