National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
The role of F420-dependent oxidoreductases in actinobacteria
Kekrt, Lukáš ; Kameník, Zdeněk (advisor) ; Palyzová, Andrea (referee)
Deazaflavin F420 is an unusual cofactor involved in oxidoreduction reactions in the cells of some microorganisms. The role of F420/F420H2-dependent oxidoreductases has been extensively described in the case of central archaeal metabolism, particularly those of methanogens. In contrast, our knowledge of these enzymes in actinobacteria is limited. This work focuses on the characterization of selected actinobacterial oxidoreductases from luciferase-like hydride transferase family, which putatively use the F420 cofactor. Specifically, Apd6 biosynthetic proteins and their sequence homologs were studied. Three recombinant proteins were prepared and purified and their enzymatic activity was tested in the presence of F420 and a set of putative substrates by means of in vitro reactions. The reaction products were monitored by liquid chromatography with UV and mass spectrometry detection. Some of the expected reaction products were detected in in vitro reactions, confirming that the proteins were catalytically active. Furthermore, one of the proteins surprisingly exhibited an unusual reaction specificity. Key words: Specialized metabolism, actinobacteria, F420 cofactor, redox reactions, reaction specificity, 4-alkyl-L-proline derivates.
Molecular mechanisms of virulence regulation in Staphylococcus aureus
Kekrt, Lukáš ; Tkadlec, Jan (advisor) ; Botka, Tibor (referee)
Staphylococcus aureus is one of the most common causes of bacterial infection in human. The bacterium is equipped by the broad spectrum of virulence factors, including modulators of immune response and also invasion factors able to destroy human cells and tissues. S. aureus is also able to asymptomatically colonize healthy individuals. Precise regulation of virulence factor expression is crucial for S. aureus survival. The aim of this thesis is to describe in detail molecular mechanisms regulating S. aureus virulence factor expression. Among these mechanisms belongs quorum sensing dependent agr system, sigma B general stress response, Sar family of transcription factors and metabolism- dependent regulators CodY and CcpA. Keywords: S. aureus, virulence, quorum sensing, agr systém, sar, sigma B, CodY, alpha-hemolysin.

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