|
|
The effect of selected endogenous and exogenous factors on bacterial growth
Šiková, Michaela ; Krásný, Libor (advisor) ; Valášek, Leoš (referee) ; Vopálenský, Václav (referee)
The growth of bacteria by binary division is a key characteristic of these organisms. This growth depends on two types of factors: endogenous and exogenous. Endogenous factors make up the molecular apparatus of cells. Among important endogenous factors belong also those involved in gene expression and its regulation. Exogenous factors are external conditions such as nutrient availability, temperature, pH, various stresses or the presence of antibacterial agents. The main aim of my Thesis was to study the effects of selected endogenous and exogenous factors on bacterial growth. As endogenous factors I studied RNase J1 in Bacillus subtilis and a small RNA called Ms1 in Mycobacterium smegmatis, which are involved in regulation of gene expression at the transcriptional level. I showed that RNase J1 can, besides its role in RNA degradation, play a role in genome integrity by removing stalled RNA polymerase (RNAP) complexes from DNA. I further showed that Ms1 binds to the RNAP core and affects the level of RNAP in the cell. The results revealed new mechanistic aspects of the transcription apparatus and show how individual components or their combinations affect bacterial growth. As exogenous factors I studied the recently discovered antibacterial compounds, called lipophosphonoxins, their interaction...
|
|
|
The function of ClpX chaperone in bacteria
Kýr, Jan ; Balíková Novotná, Gabriela (advisor) ; Šiková, Michaela (referee)
Intracellular proteolysis is an essential regulatory process that affects cellular physiology. Since proteolysis destroys proteins irreversibly, this process must be strictly controlled. The AAA+ proteins are the key factors in regulated proteolysis in bacteria. These proteins consist of two functional domains, the AAA+ chaperone domain and the protease domain. One particular group of these AAA+ protein is the Clp protein family. Functional domains of the Clp family are formed by seperate proteins. The hexameric unfoldase ClpX is a member of this protein family. This unfoldase can interact with the highly conserved ClpP protease to form a ClpXP proteolytic complex. This proteolytic complex utilizes the energy of ATP binding and hydrolysis to unfold and translocate the specifically tagged substrate into the ClpP degradation chamber. Substrate recognition is mediated by the binding of ClpX to short unstructured sequences called degradation tags. ClpX recognizes several degradation tags, but the most important one is recognition of the ssrA degradation tag, which is the output of the tmRNA ribosome rescue system. Although ClpX interacts with ClpP, it affects a variety of cellular processes such as the expression of virulence factors or the adaptation to stress factors, ClpX can work independently of...
|
guest ::
RSS feed.