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Identification of type III secretion effectors in Aeromonas spp.
Jirsová, Anežka ; Kamanová, Jana (advisor) ; Lišková, Petra (referee)
Bacteria of the genus Aeromonas are Gram-negative, rod-shaped bacteria that are ubiquitous in the aquatic environment. The mesophilic species of this genus, represented by A. hydrophila, A. dhakensis, A. veronii and A. schubertii, are not only important pathogens in fish but also emerging pathogens in humans. They are associated with various gastrointestinal, systemic and wound infections. Their virulence has been described as multifactorial and associated with the presence of a type 3 secretion system. However, not much is known about the effector proteins that are introduced into the host cell by this system. The aim of this work was to characterize the two different type 3 secretion systems API-1 and API-2 of A. schubertii with respect to their cellular cytotoxicity and to identify the effector proteins that they transport into the host cell. To achieve these goals, a variety of methods were used, including microbiological techniques, molecular cloning, tissue culture techniques, SDS polyacrylamide gel electrophoresis, and mass spectrometry. Successful construction of mutant strains of A. schubertii with inactivated API-1 or API-2 and a strain with deletion of the gene encoding the negative regulator of API-1 enabled me to identify potential type 3 effector proteins of this species. Among the...
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Molecular mechanisms of bacterial persistence to antibiotics
Jirsová, Anežka ; Lichá, Irena (advisor) ; Branny, Pavel (referee)
The ability to persist is inherent in the vast majority of bacterial species. Persisters represent a small heterogenous fraction of the bacterial population that can tolerate antibiotics. Unlike resistant cells, which are genetically distinct from the rest of the antibiotic-sensitive population, persister cells form a genetically indistinguishable subpopulation. Persisters arise either as a result of stress caused by adverse environmental conditions, or persister subpopulation arise as a result of stochastic induction independent of the presence of stressful conditions. There are various mechanisms by which bacterial cells have been shown to induce a persistent state. Toxin-antitoxin systems and their interaction with stringent response effectors play an important role during the development of persistence. The persistent state is also affected by changes in proton-motive force (PMF) and the fluctuations in the gene expression level of energy generating enzymes of the Krebs cycle (TCA). In this thesis, persister cells are characterized and the current knowledge about the molecular mechanisms leading to the induction of persistence in bacteria is summarized. Key words: bacteria, persistence, antibiotics, stringent response, PMF, TCA
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