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Mise en évidence de gènes d'amibes libres impliqués dans l'interaction avec des bactéries intracellulaires

Abstract : Free-living amoebae are protists who colonize natural and artificial environments. Some strains of the genus Acanthamoeba are human pathogens. In addition, in response to environmental stresses, amoebae can differentiate into a resistant form called cyst, protecting them from adverse conditions. Free-living amoebae are described as environmental reservoirs for many bacterial pathogens, such as Legionella pneumophila, a bacteria responsible for a serious form of pneumonia, called legionellosis. During this study, we were interested in the genes of A. castellanii that could be involved in amoebal physiology, especially encystment, and during interaction with L. pneumophila. For this purpose, several proteins of A. castellanii were selected from a proteomic analysis of L. pneumophila infected amoebae. The gene overexpression in the amoeba did not affect the intracellular growth of L. pneumophila. However, the overexpression of two of these genes partially inhibited the encystment process. One of them, the Erat protein, was analyzed in more details. It is an N-acetyltransferase-like of the GNAT family, has a potential prokaryotic origin, and its expression was strongly repressed during encystment. To conclude, this work led to the development of molecular tools on the A. castellanii model, as well as to improve knowledge on the amoebal physiology and in particular on the encystment process.
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Steven Rolland. Mise en évidence de gènes d'amibes libres impliqués dans l'interaction avec des bactéries intracellulaires. Biochimie, Biologie Moléculaire. Université de Poitiers, 2019. Français. ⟨NNT : 2019POIT2281⟩. ⟨tel-02618519⟩

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