This study explores Franco-Papal relations, and their effect on the French Church and State, from Henri IV's conversion to Roman Catholicism in 1593 until his death in 1610. Because Henri IV's primary concern, even in matters involving the Papacy or the Gallican Church, was to protect his kingdom from Habsburg encroachment, he was willing either to abandon his Protestant allies abroad, or to adopt reform measures, such as the decrees of the Council of Trent, that might weaken his own authority or disturb the peace of his kingdom. This caused repeated conflicts with the Counter-Reformation Popes Clement VIII and Paul V, to whom the primary enemy was always the infidel and the heretic. Nevertheless both sides realized that they needed each other to maintain their independence of Spain.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

O sistema de secreção tipo IV (T4SS) da família de bactérias Xanthomonadaceae transfere efetores (X-Tfes) com a capacidade de matar outras bactérias, conferindo uma vantagem em comunidades bacterianas mistas para colonizar diferentes nichos como o solo ou as superfícies das plantas. Os X-Tfes possuem diferentes domínios putativos com atividades hidrolíticas contra componentes do envelope celular bacteriano do tipo: glicohidrolases, transglicosilases, amidases e lipases. Os X-Tfes por sua atividade biológica inata podem ocasionar dano intracelular para a bactéria que os produz. Para se proteger contra estas atividades, também são produzidas lipoproteínas com função inibitoria (X-Tfis) localizadas no periplasma. Os genes que codificam os X-Tfes e os X-Tfis estão organizados em operons, o que permite gerar os pares efetor/inibidor simultaneamente. Entre os potenciais X-Tfes do fitopatógeno Xanthomonas citri estão Xac1918 e Xac0574. Xac1918 é uma proteína com um domínio da superfamília da lisozima e um domínio conhecido como RTX (Repeats in Toxin) de ligação ao cálcio, enquanto Xac0574 tem um domínio da superfamília da lipase 3. Os seus possíveis inibidores, Xac1917 e Xac0573 respectivamente, apresentam um peptídeo sinal no N-terminal contendo o lipobox representativo das lipoproteínas. As proteínas Xac0574 e Xac0573 são monômeros em solução que formam um complexo estável 1:1, favorecido termodinamicamente (ΔG°= -12 Kcal/mol) com uma constante de dissociação de 2,45 nM, garantindo que a bactéria fique protegida contra os efeitos nocivos de Xac0574 quando é produzida intracelularmente. Xac0574 é uma fosfolipase A1, sem atividade lisofosfolipase, com a capacidade de hidrolisar os três fosfolipídios majoritários que compõem a membrana celular bacteriana, fosfatidilglicerol (PG), cardiolipina e fosfatidiletanolamina (PE), mostrando uma aparente preferência pelo último. A atividade enzimática de Xac0574 explica a forte inibição do crescimento celular em E. coli após da sua indução heteróloga, já que gera uma diminuição de quase 10 vezes da população celular comparada com a cultura não induzida com a mesma construção. Poroutro lado, Xac0573 inibe efetivamente a atividade enzimática de Xac0574 ao formar o complexo, além de não ter atividade fosfolipase nem lisofosfolipase. Foram produzidos cristais da Xac1918 e Xac0573 que difrataram com uma resolução de 3,0 e 2,5 Å, respectivamente. Porém, só foi gerado um modelo de Xac0573. Xac0573 está composta por duas folhas β antiparalelas com uma topologia característica de β sanduíche Com uma pequena hélice e duas voltas. Um alinhamento de homólogos de Xac0573 identificou nas extremidades da proteína as regiões conservadas, constituindo duas possíveis interfaces de interação que podem ser as responsáveis por bloquear o acesso dos fosfolipídios ao sítio catalítico ou impedir os rearranjos estruturais de Xac0574 que são necessários para a sua atividade enzimática. Adicionalmente, a topologia da Xac0573 é semelhante do domínio C2, conhecido em eucariotos como domínio de ligação ao lipídio e ao cálcio, e está envolvido em processos de sinalização de segundos mensageiros lipídicos, proteínas de trafego de membranas e mecanismos de fusão de membranas. Nossos resultados apontam para uma nova função biológica do domínio C2 como um inibidor enzimático intracelular em bactérias. / The type IV secretion system (T4SS) of the bacteria family Xanthomonadaceae transfers effectors (X-Tfes) with that can kill other bacterial cells, conferring an advantage to the bacterial community during colonization of different niches in the soil or on the plant surface. The X-Tfes possess different putative domains with hydrolytic activity against components of the bacterial cellular envelope, including glycohydrolase, transglycolase, amidase and lipase domain. The innate biological activity of X-Tfes can cause intracellular damage. Therefore, the bacteria that produce them also produce lipoproteins with inhibitor function (X-Tfis) located in the periplasm for their protection. The genes that code for X-Tfes and X-Tfis are organized in operons that allow for their simultaneous expression. Among the X-Tfes of the phytopathogen Xanthomonas citri are Xac1918 and Xac0574. Xac1918 is carries a lysozyme superfamily domain, as well as a domain known as RTX (Repeats in Toxic) predict to bind calcium, while, Xac0574 has a domain belonging to the lipase 3 superfamily. Their possible inhibitors, Xac1917 e Xac0573 respectively, carry an N-terminal signal peptide containing a lipobox found in bacterial lipoproteins. The Xac0574 and Xac0573 proteins are both monomers in solution, They can form a stable 1:1 complex, that is thermodynamically favored (ΔG°= -12 Kcal/mol) with a dissociation constant of 2,45 nM. This affinity ensure that the bacterium is protected against the harmful effects of Xac0574 when it is produced intracellularly. We show that Xac0574 is a phospholipase A1, without lisophospholipase activity, and is able to hydrolyze the three most common phospholipids found in the membranes of Gram negative bacteria, namely phosphatidylglycerol (PG), cardiolipin and phosphatidylethanolamine (PE), presenting an apparent preference for PE. The enzymatic activity of Xac0574 explains the strong inhibition of growth of E. coli cells after its heterologous induction: a nearly 10-fold decrease in the cell population is observed when compared to the non-induced culture with the same construct. On the other hand, Xac0573 effectively inhibits the enzymatic activity of Xac0574. Furthermore, Xac0573 does not possess when forming the complex, besides not having phospholipase nor lysophospholipase activity.Crystals of Xac1918 and Xac0573 were produced which diffracted with to resolution of 3.0 and 2.5 Å, respectively. However, we were able to resolve the structure of only Xac0573. Xac0573 is composed of two anti-parallel sheet that form a β-sandwich with three small helices. An alignment to Xac0573 homologs identified conserved regions at the ends of the protein that constitute two possible interfaces of interaction that may be responsible for blocking the access of the phospholipids to the catalytic site or impede the structural rearrangements of Xac0574 that are necessary for its enzymatic activity. Additionally, the topology of Xac0573 is similar to that to C2 domains, known in eukaryotes to bind lipids and calcium and to be involved in signaling processes mediated by lipid second messengers, membrane trafficking and membrane fusion mechanisms. Our results point to a new biological function of the C2 domain as an intracellular enzyme inhibitor in bacteria.

O presente trabalho tem como objetivo analisar a concepção, formalização e ocupação da Marquise do Parque Ibirapuera, através de uma trajetória que se inicia com a definição do programa de necessidades para as comemorações do IV Centenário da cidade de São Paulo, na década de 50 do século passado. Onde foi tomada a decisão de realizar a construção do que seria o maior parque público da cidade, somado a um conjunto edificado que centralizaria a maioria das atividades propostas durante o período de festividades. Ao mesmo tempo que essa grande obra deveria mostrar a força do progresso do Estado, serviria de legado as próximas gerações. Assim, a construção do programa funcional e sua posterior concepção arquitetônica, de autoria de Oscar Niemeyer e equipe, se mostram fundamentais como fonte de análise para entender o surgimento do elemento de ligação, a grande marquise, entre os pavilhões temáticos propostos. A primeira parte do trabalho examina a evolução do projeto, seus precedentes e as adversidades enfrentadas durante o período de construção. A segunda parte diz respeito a observação e coleta de dados das atividades realizadas sob esta grande cobertura após a conclusão de sua construção. Demonstrando, através de uma amostragem significativa, sua capacidade de servir de suporte a inúmeros usos, sejam eles programados ou espontâneos, no decorrer dos ultimos 60 anos. Superando seu programa inicial de ligação e suporte aos pavilhões com que está conectado e se consolidando como um lugar de intenso convívio social e de encontros, aberto a imprevisibilidade, ao uso indeterminado. / This study aims to analyze the design, formalization and occupation of the Ibirapuera Park\'s Great Marquee, through a trajectory that begins with the definition of the architectural brief for the IV Centennial of the city of São Paulo celebrations in the 1950\'s. Then was the decision to undertake the construction of what would be the largest public park in the city, plus a built set centralizing most of the proposed activities during the festivities. At lhe same time this great work should show the strength of the State\'s progress, it would serve as a legacy to future generations. Thus, the construction of functional program and subsequent architectural design of Oscar Niemeyer and team, show up as a source of fundamental analysis to understand the emergence of the connecting element, a large marquee, between the proposed thematic pavilions. Showing the evolution of the design, its precedents and adversities during the construction period. Conforming the first part of this work. The second part of the work is concerned with the observation and data collection of the activities performed under this great cover upon completion of its construction. Demonstrating, through a significant sample size, its architectural ability to provide support to a number of uses, whether preprogrammed or spontaneous, over the last 60 years. Overcoming its initial briefing as a connection and support to the pavilions, it consolidates itself as a place of intense social life and meeting, open to unpredictability, to the indefinite use.

Introdução: A sitagliptina, inibidor da dipeptidil-peptidase IV, impede a degradação do GLP-1 (peptídeo-1 semelhante ao glucagon), um dos principais hormônios incretínicos. A dieta interfere na secreção de GLP-1, no entanto, a interação das drogas que aumentam o GLP-1 e os macronutrientes da dieta é pouco estudada. Objetivo e Métodos: Determinar o efeito da sitagliptina, na secreção de GLP-1, glucagon, insulina, peptídeo-C, ácidos graxos livres e na glicemia após três dietas, isocalóricas, de diferentes composições nutricionais em pacientes diabéticos tipo 2, recém-diagnosticados, virgens de tratamento, quando comparado a uso de placebo. Dezesseis indivíduos nessas condições foram submetidos a dietas hiperglicídica, hiperprotêica e hiperlipídica, isocalóricas entre si. Dosaram-se nos tempos 0, 30, 60, 120 e 180 minutos os parâmetros: glicose, insulina, peptídeo C, GLP-1, glucagon e AGL. Foi calculada média de área sob a curva e cálculo da área incremental, além de análise de variância para medidas repetidas. Resultados: Durante o teste de dieta hiperglicídica a glicemia foi maior em todos os tempos quando comparado aos testes com PTN e LPD independentemente do uso de sitagliptina (p<0,05). Sitagliptina diminuiu a glicemia em todos os tempos, quando comparado ao uso de placebo (p<0,05). Durante a dieta CHO, a secreção de glucagon foi menor que nas dietas LPD e PTN (p<0,05). Já a concentração de insulina foi maior com a dieta CHO em relação à dieta LPD (p<0,05). A concentração de insulina e peptídeo C foi maior em todos os tempos na dieta CHO (p<0,05). A concentração de GLP-1 foi significativamente maior durante o teste hiperlipídico em relação à dieta CHO. Durante a dieta LPD, a medida de GLP-1 foi maior em todos os tempos. A dieta CHO apresentou medida de GLP-1 menor em todos os tempos do que as outras dietas (p<0,05). A medida de GLP-1 no tempo foi maior (até 120\') com o uso de sitagliptina do que com o uso do placebo, apesar de não estatisticamente significativa. Os níveis de AGL no tempo foram maiores com o uso do placebo do que com o uso da sitagliptina, apesar de não estatisticamente significativo. Conclusão: Houve diminuição da glicemia em todos os tempos com sitagliptina, independentemente da dieta testada. Houve diminuição do efeito da sitagliptina durante o uso da dieta hiperglicídica / Background: Sitagliptin, a dipeptidil-peptidase IV inhibitor, prevents the degradation of GLP-1 (glucagon-like peptide 1), one of the incretin hormones. It is well-known that diet interferes in the GLP-1 secretion; however, the interaction between drugs that stimulates the release of GLP-1 and the macronutrients from diet is hardly studied. Objective and Methods: To demonstrate the effect of sitagliptin on glycemia, and on the secretion of GLP-1, glucagon, insulin, C-peptide, and free fatty acids after three isocaloric diets with different nutritional compositions, in drug-naïve patients, newly diagnosed with type 2 diabetes, when compared to the use of placebo. Sixteen individuals were subjected to a high-carbohydrate diet, a high-protein diet, and a high-fat diet, all of which with similar caloric values. At 0, 30, 60, 120 and180 minutes after the diet, glucose, insulin, C-peptide, GLP-1, glucagon, and AGL were measured. The mean area under the curve, the incremental area, and the variance for repeated measures were calculated. Results: During high-carbohydrate diet, glycemia was higher for all time points, when compared to the PTN and LPD diets, independently of sitagliptin (p<0,05). Sitagliptin reduced glycemia during three diets when compared to placebo (p<0,05). During CHO diet, secretion of glucagon was smaller than it was during the LDP and PTN diets (p<0,05). On the other hand, insulin concentration was higher than during the LPD diet (p<0,05). Concentrations of insulin and C-peptide were higher for all the time points during the CHO diet (p<0,05). GLP-1 concentration was significantly higher during the high-fat diet than during the high-carbohydrate diet. During the LPD diet, the quantity of the GLP-1 was larger for all time points. The CHO diet presented lower GLP-1 level, for all the time points, than the other diets (p<0,05). The GLP-1 level (up to 120min) with the use of sitagliptin was higher with LPD and PTN diet than it was with the CHO diet. The AGL levels for all time points were higher with placebo than with sitagliptin, although not statistically significant. Conclusion: There was a reduction in glycemia with sitagliptin, independently of the diet tested, for all time points. There was a reduction in sitagliptin effect during the use of the high-carbohydrate diet

Das phylogenetisch weit verbreitete RNA-bindende Protein Hfq ist an einer Vielzahl von Prozessen innerhalb des bakteriellen RNA-Metabolismus, insbesondere im Rahmen der post-transkriptionellen Genregulation durch kleine RNAs (sRNAs) beteiligt. Hfq-Proteine zählen zu der Familie der Sm- und Lsm-Proteine und zeichnen sich strukturell durch die funktionelle Ausbildung ringförmiger Homohexamere aus. Cyanobakterielle Orthologe zeigen gegenüber den gut untersuchten Hfq-Proteinen aus E. coli und anderen Proteobakterien eine schwache Sequenzkonservierung und bieten auch daher einen interessanten Ansatzpunkt für die Untersuchung riboregulatorischer Prozesse in diesen Organismen. In der vorliegenden Arbeit werden einleitende Untersuchungen zu Funktion und Struktur des orthologen Hfq-Proteins aus dem einzelligen Modell-Cyanobakterium Synechocystis sp. PCC 6803 vorgestellt. Die Inaktivierung des hfq-Gens (ssr3341) führte in diesem Organismus zum Verlust der phototaktischen Motilität. Mithilfe elektronenmikroskopischer Analysen konnte dieser Phänotyp auf das Fehlen von Typ IV Pili zurückgeführt werden. Microarray-Analysen wiesen in der deltahfq-Mutante für 31 Gene eine veränderte, in den meisten Fällen reduzierte Transkriptakkumulation nach. Am stärksten betroffenen waren Gene bzw. Operone, welche dem Regulon des cAMP-Rezeptorproteins Sycrp1 zugeordnet werden und zum Teil nachweislich an der Motilität von Synechocystis-Zellen beteiligt sind. Weitere vergleichende Expressionsanalysen identifizierten mithilfe eines speziellen Tiling-arrays ferner zwei „intergenisch“ kodierte potenzielle sRNAs, Hpr1 und Hpr3, deren Transkriptmengen signifikant von der hfq-Inaktivierung beeinflusst werden. Kristallstrukturdaten deuten zusammen mit den Ergebnissen aus in vitro-Bindungsstudien und genetischen Komplementierungsexperimenten - trotz starker Konservierung zentraler struktureller Charakteristika - neuartige biochemische und funktionelle Eigenschaften des Hfq-Proteins aus Synechocystis sp. PCC 6803 an. Funktionelle Implikationen werden im strukturellen und phylogenetischen Kontext diskutiert. / The phylogenetically conserved RNA binding protein Hfq is a key player in bacterial RNA metabolism, particularly with regard to sRNA-mediated post-transcriptional gene regulation. Hfq proteins belong to the well-conserved family of Sm- and Lsm proteins and are characterized by the formation of homo-hexameric ring-shaped structures. In comparison with well-studied Hfq proteins from E.coli and other proteobacteria the cyanobacterial orthologues show rather poor sequence conservation. Therefore, they provide a quite interesting background for analyzing riboregulatory processes in these organisms. In this work, the orthologous Hfq protein from the unicellular model cyanobacterium Synechocystis sp. PCC 6803 has been initially characterized on the functional and structural level. Insertional inactivation of the hfq gene (ssr3341) led to a non-phototactic phenotype that was due to the loss of type IV pili on the cell surface, as demonstrated by electron microscopy. Microarray analyses revealed a set of 31 genes with altered transcript levels in the knock-out mutant. Among the most strongly affected genes, there were members of two operons that had previously been shown to be involved in motility, controlled by the cAMP receptor protein Sycrp1. Further comparative transcriptional analyses using custom tiling arrays revealed two putative sRNAs (Hpr1 and Hpr3) from intergenic regions, whose transcript levels appeared to be significantly affected by hfq-inactivation. Structural analyses, genetic complementation as well as RNA-binding studies in vitro indicate that the Hfq orthologue from Synechocystis sp. PCC 6803 exhibits novel biochemical and functional properties, though retaining general structural features of its proteobacterial counterparts. Functional implications are discussed with regard to structural und phylogenetic considerations.

Cette recherche interroge la monarchie française en situation de crise en partant d’un pari politique hors norme, celui des prélats catholiques qui misèrent sur Henri IV, roi protestant. Elle étudie les diverses facettes de l’action politique de ces hommes et reconstruit les mécanismes de leur travail de légitimation du premier Bourbon, en privilégiant les premières années du règne. Centrer l’enquête sur ces années permet de restituer à cette période sa dimension d’incertitude vécue par les acteurs de la monarchie, qui se trouve généralement écrasée par le poids de l’histoire de la pacification, après l’édit de Nantes. Ce choix d’un temps court rend possible l’étude attentive des cérémonies possédant une grande importance symbolique, tels que l’abjuration et le sacre royaux. Trop souvent ces événements sont uniquement décrits, racontés par l’historiographie. L’analyse proposée ici s’attache à l’inverse à leur redonner leur dimension problématique, à réfléchir sur les choix stratégiques faits par le pouvoir, notamment en ce qui concerne leur publication, comme une seconde mise en scène, imprimée. En adoptant un angle d’observation centré sur l’engagement, tantôt exposé, tantôt discret du groupe de prélats (Jacques du Perron, Claude d’Angennes et leurs pairs), il devient possible d’appréhender la monarchie en tant qu’œuvre collective d’acteurs multiples qui agissent pour assurer sa survie. En proposant ainsi une alternative à la vision navarro-centrée qui domine largement l’historiographie, cette approche permet d’aborder d’une nouvelle façon la sortie des guerres de Religion et de révéler des acteurs peu connus, qui néanmoins jouent un rôle crucial dans ce processus. / This dissertation investigates the French monarchy during a moment of crisis, focusing on an exceptional political bet made by a number of catholic prelates who chose to support Henri IV, a Protestant king. Their varied political actions are studied here, and the mechanisms of their work of legitimation of the first Bourbon are reconstructed, with a particular attention to the first years of his reign. The emphasis on these years offers the opportunity to give back to this period its dimension of uncertainty, as lived by the actors of the monarchy, a dimension that is generally erased under the weight of the history of the pacification, beginning with the Edict of Nantes. The choice of a short period allows a careful analysis of ceremonies of great symbolic importance, such as the royal abjuration and coronation. Too often these events have been merely narrated by historiography. This analysis, however, seeks to reconstruct their problematic dimension. Specific attention will be paid to the choices made when these events were published, which constituted a second staging of the act in printed form. With the focal point placed on the political commitment of the prelates, which at times was explicit, and at other times remained discreetly hidden away, it becomes possible to understand the monarchy as the collective work of multiple actors who endeavoured to ensure its survival. Thus, by proposing an alternative reading of events to the Navarro-centric vision that largely dominates historiography, this approach discusses the end of the Wars of Religion from a new perspective, which uncovers lesser known actors, who nonetheless played a crucial role in this process.

Le corps calleux (CC) est la principale commissure cérébrale connectant les aires corticales homologues des deux hémisphères chez les vertébrés placentaires. Les malformations du corps calleux (MCC) représentent la malformation cérébrale la plus fréquente à la naissance et sont présentes chez 5% des individus avec anomalie neuro-développementale. Une meilleure connaissance de l’ontogenèse du corps calleux et de ses causes génétiques devrait permettre d’ouvrir la voie à des corrélations cliniques pour un meilleur conseil génétique. Cet aspect constitue probablement l’enjeu de la prochaine décennie concernant les foetus avec MCC. Le travail de thèse a porté sur 138 foetus avec MCC, pour lesquels nous avons fait un examen foeto-neuropathologique et une classification en plusieurs catégories. Au total, ce travail a permis : 1/le démantèlement des causes génétiques des MCC par une triple approche de CGH array, d’exome en trio et de panels ciblés, avec une augmentation considérable des causes identifiables de MCC au sein de cette cohorte, 2/ l’identification et la caractérisation fonctionnelle d’un nouveau gène de ciliopathie dans un phénotype extrême ; 3/ l’identification de 3 nouvelles mutations de ZBTB20, récemment identifié comme responsable du syndrome de Primrose, démontrant que ce syndrome est une cause fréquente de MCC et permettant une description clinico-radiologique plus précise. 4/ L’identification de plusieurs gènes candidats en cours de validation. / Corpus callosum is the main cerebral commissure connecting homologous cortical areas in placental mammals. Malformations of corpus callosum (MCC) are the most frequent brain malformation at birth and are present in 5% of patients with neurodevelopmental delay. A good knowledge of genetics of corpus callosum development should pave the way to better clinical correlations for a more accurate genetic counselling. This is the challenge of the next decade. This thesis concerns a cohort of 138 fetuses with MCCs, well classified on neuropathological examination. It allowed 1/ to unravel the genetic causes of MCC through a triple approach combining CGH array, whole exome and NGS panels sequencing, with a considerable increase in the number of causes of MCC identified ; 2/ identification of a new gene in an extreme ciliopathy phenotype; and 3/ identification of novel ZBTB20 mutations , a gene recently identified as responsible for Primrose syndrome, showing that this syndrome is frequent among MCCs and allowing a precise clinico-radiological description of the syndrome. 4/ Several new candidate genes are under study.

Das humane Magenpathogen Helicobacter pylori (H. pylori) besiedelt den menschlichen Magen und kann zu der Entstehung schwerwiegender Krankheiten wie Magenkrebs und Magengeschwüren führen. Die Pathogenese ist eng mit dem bakteriellen Typ IV Sekretionssystems (T4SS) assoziiert, das die Translokation des Effektorproteins CagA in die Wirtszelle vermittelt. Bisher ist noch unbekannt, in welchem Ausmaß wirtszellspezifische Faktoren die T4SS induzierte Pathogenese beeinflussen. Dieser Aspekt wurde in dieser Arbeit durch die Analyse verschiedenster Zelllinien das erste Mal systematisch untersucht. Interessanterweise unterschied sich die zelluläre Antwort auf die T4SS spezifische Infektion erheblich in Abhängigkeit der verwendeten Zelllinie. Die Ergebnisse beweisen, dass Wirtszellfaktoren eine ebenso große Rolle in der H. pylori induzierten Pathogenese spielen wie bakterielle Effektoren. Zusätzlich wurde in dieser Arbeit eine genomweite Screening-Methode etabliert, die es ermöglicht, neue Komponenten des T4SSs, translozierte NF-B Effektoren und bakterielle Adhäsine zu identifizieren. Auch der Einfluss von CagA auf den EGF-Rezeptor wurde hier näher untersucht. Der Rezeptor steht ebenfalls eng mit der Entstehung von Krebs in Verbindung. Hierbei stellte sich heraus, dass CagA die Endozytose des EGF-Rezeptors durch die Aktivierung der Nicht-Rezeptor Tyrosinkinase c-Abl hemmt und dadurch die Rezeptorpopulation auf der Wirtszelloberfläche erhöht. Interessanterweise führt dieser Effekt jedoch nicht zu einer Verstärkung der EGF-Rezeptor Signaltransduktion. Vielmehr kommt es zu einer Hemmung der EGF-Rezeptor Transaktivierung und zu einer Blockade der EGF vermittelten Wundheilung. Die Daten weisen auf eine Rolle des EGF-Rezeptors in der H. pylori induzierten Geschwürbildung hin. Auch der zu Grunde liegende molekulare Mechanismus der Rezeptor-Inhibierung konnte hier entschlüsselt werden, der sowohl von CagA als auch von der Phosphatase SHP-2 gesteuert wird. / The human gastric pathogen Helicobacter pylori (H. pylori) elicits a tremendous medical burden because of its causative association with peptic ulcer disease and gastric cancer. The pathogenic potential of H. pylori is intricately linked to the expression of a pathogenicity island encoded type IV secretion system (T4SS), which translocates the bacterial effector protein CagA into the eukaryotic host cell. The role of host cell determinants in T4SS mediated pathogenesis has not yet been systematically examined. To elucidate the role of host cell factors within T4SS induced host cell responses, different eukaryotic cell lines were analyzed systematically for respective phenotypes. Remarkably, T4SS mediated host responses among these cell lines varied considerably, thereby demonstrating the importance of host cell components in H. pylori induced pathogenesis. In addition, a H. pylori genome wide bacterial screen for factors important in pathogenesis, such as unknown T4SS components or novel NF-kappaB effector molecules, was developed and optimized. The precise function of the prominent effector protein CagA remains unclear. To functionally characterize the role of CagA, its impact on the epidermal growth factor (EGF)-receptor pathway was analyzed. The results suggest a mechanism where EGF-receptor endocytosis is completely blocked by a CagA induced activation of c-Abl, leading to an elevated receptor surface exposition. Surprisingly, EGF-receptor transactivation and EGF-dependent wound healing are selectively blocked during prolonged infections as well, indicating that an increased receptor-population on the cell surface does not necessarily promote signaling. This data suggests a role for the EGF-receptor in H. pylori- induced ulcer disease. The underlying molecular mechanism was identified as being SHP-2 and CagA dependent.

Les études d'interaction protéine-ligand aident à mieux comprendre la structure et la fonction des protéines. Dans la première partie de la thèse, la cyt bd oxydase a été étudiée. La protéine d'E. coli a été immobilisée avec succès sur des électrodes modifiées par des nanoparticules d'or. Ainsi, un biocapteur électrochimique a été créé, permettant de tester certains inhibiteurs potentiels de cyt bd provenant d’E. coli. Le cyt bd issue de G. thermodenitrificans thermophile a également été étudié. En faisant appel aux spectroscopies IR et Raman ainsi que l’électrochimie, il a été démontré que la protéine est distincte du cyt bd d’E. coli. Une influence mutuelle du pH et de la température sur la catalyse a été aussi démontrée. La deuxième partie de la thèse portait sur la protéine mitochondriale mitoNEET. L'influence du pH et de divers ligands (pioglitazone, resvératrol, ions phosphates) a été examinée. / Protein-ligand interaction studies help to better understand the structure and function of proteins. In the first part of the thesis cyt bd oxidase was studied. The protein from E. coli was successfully immobilised at gold nanoparticles modified electrodes. Thus, an electrochemical biosensor was created allowing testing some potential inhibitors of cyt bd from E. coli. The cyt bd from thermophilic G. thermodenitrificans was also studied. By means of IR, Raman spectroscopy and electrochemistry the protein was shown to be distinct from cyt bd from E. coli. A mutual influence of pH and temperature was demonstrated on the electrochemical and catalytical properties. The second part of the thesis focused on mitochondrial mitoNEET protein. The influence of the pH and various ligands was studied.