National Repository of Grey Literature 33 records found  previous11 - 20nextend  jump to record: Search took 0.01 seconds. 
The role of Spr1851 protein Streptococcus pneumoniae in cell division
Jarošová, Václava ; Ulrych, Aleš (advisor) ; Seydlová, Gabriela (referee)
The role of Spr1851 protein Streptococcus pneumoniae in cell division Human extracellular pathogen S. pneumoniae encodes unique serin/threonine protein kinase of Eucaryotic type StkP and its cognate phosphatase PhpP. This kinase affects number of cellular processes including virulence, competence, cell division and cell wall synthesis by phosphorylating its substrates. Hypothetical protein Spr1851 named Jag was identified as a new StkP substrate in the membrane fraction by comparing the wild-type phosphoproteomes with StkP deleted strain. This protein consists of three domains and an interdomain region that contains T89 phosphorylation site. There is a Jag_N domain with an unknown function at the N-terminus. The C-terminus contains two domains - KH and R3H, which are highly conserved and their expected function is binding of nucleic acid. The main aim of this work is to explain the function of Jag protein, to determine the effect of individual domains on the phenotype and the localization of the protein and to determine the role of phosphorylation on T89. The results confirm that Jag protein could play a role in cell division or cell wall synthesis. Furthermore, the results indicate that the Jag_N domain is essential for the localization of the protein into the membrane, whereas the KH and R3H domains are...
General stress response in Staphylococcus aureus and its role in adaptation to hyperosmotic stress
Kotková, Hana ; Lichá, Irena (advisor) ; Seydlová, Gabriela (referee)
Hyperosmotic stress induces a stress reponse in a halotolerant bacteria Staphylococcus aureus that helps it to survive even the osmotic conditions that are inhibiting for most of the bacteria. Stress responses of S. aureus include a general stress response that activates rapidly on a wide range of stresses and is ensured by expression of genes induced by an alternative sigma B subunit of RNA polymerase (SigB), and more specific responses to hyperosmotic stress associated with transporters of potassium and transporters of compatible solutes. Also, some virulence factors (such as the adhesive Ebh protein) allow S. aureus to survive hyperosmotic stress within the host, thereby helping to colonize it. It is currently known that the general stress response directly and indirectly participates in the specific stress adaptation through the Kdp transport system for potassium (Kdp transporter) and transporters of compatible solutes (PutP and OpuD). Expression of the Kdp transporter and the large S. aureus Ebh protein is SigB dependent, via Agr or ArlRS virulence regulator systems. The formation of a biofilm, in which SigB is significantly involved, may also enable to colonize host niches with low water activity. Hyperosmotic stress by triggering SigB initiates a complex response that is associated not only...
Study of biofilm formation of bacterial isolates from milk and dairy products
Nováková, Veronika ; Demnerová, Kateřina (advisor) ; Seydlová, Gabriela (referee)
Bacterial biofilm is a complex community of microbial cells, which are embed into the extracellular pollysacharide matrix. Typical ability of the biofilm is the ability to adhere to either abiotic, or biotic surfaces. The formation of biofilm is a dynamic process, which finally formes a 3D multicellular complex. The initial phase is called the adhesion. After that process is done, the extracellular polymeric matrix is produced to create living conditions of bacteria in biofilm. Biofilm has hight level of antimicrobial resistance. This resistance consists of physical and chemical barriers, which effectively block diffusion and penetration of antimicrobial substances inside the biofilm. Biofilms cause problems in food industry, where it could be origin of food contaminations. Thefore it is necessary to understand the relationship between microorganisms and materials used in food industry. Key words: biofilm, milk and dairy products, milk and dairy industry, disifectanc, Escherichia coli, Staphylococcus spp.
Transcription regulation by sigma factors in Bacillus subtils
Benda, Martin ; Krásný, Libor (advisor) ; Seydlová, Gabriela (referee)
RNA polymerase (RNAP) is a key enzyme in regulation of bacterial gene expression. RNAP is multi-subunit enzyme and its σ subunits (factors) are used for DNA recognition. Regulation of RNAP complexed with the major σ factor has been thoroughly studied; in contrast, mechanisms of regulation of RNAP containing alternative σ factors are much less understood. This thesis is focused mainly on the model organism Bacillus subtilis and its alternative σ factors σF , σG , σI a σK . We studied the ability of RNAP in complex with these factors to recognize promoter sequences, to initiate transcription in dependence on the concentration of the initiating nucleoside triphosphate (iNTP), and to interact with selected proteins. For σF , a promoter regulated by the concentration of iNTP was discovered; for σI , to the contrary, this mechanism was not observed. In the case of σG -dependent transcription we were not able to examine regulation by the concentration of iNTP. Nevertheless, stimulation of σG -dependent transcription by a protein called YlyA, previously described in the literature, was confirmed. This stimulation was newly identified also for σF -dependent transcription. Further, we examined possible functional interaction between HelD and σK , but this link was not confirmed. Finally, this thesis...
Role of cytoplasmic membrane and cell wall in bacterial resistance to cationic antimicrobial peptides
Havlová, Noemi ; Seydlová, Gabriela (advisor) ; Vopálenská, Irena (referee)
Cationic antimicrobial peptides are part of the innate immune system of all organisms. Their properties such as structure, charge, amphipathicity and hydrophobicity make them promising agents with the potential for use not only in treatment of bacterial infections but also against some viruses, parasites, fungi and cancer cells. One of their possible targets is the cytoplasmic membrane, which they permeabilize. This mode of action has several advantages. The important feature of antimicrobial peptides is their selectivity for bacterial membranes, which makes them harmless to eukaryotic host cells. Another advantage is that the development of bacterial resistance against these peptides is more difficult since the action of antimicrobial peptides is rapid. Nevertheless, there appeared some bacterial strains that are insensitive to already used antimicrobial peptides. By using target modification resistant bacteria are able to prevent the bactericidal effects of the antimicrobial peptides. At the level of cytoplasmic membrane bacteria can alter its electrostatic or structural properties of membrane lipids and thus the antimicrobial peptides lose their ability to interact with the membrane and permeabilize it. Understanding the mode of action of antimicrobial peptides and mechanisms by which bacteria...
Construction of a genetically detoxified Bordetella pertussis strain to develope a new generation of whole-cell vaccine
Bočková, Barbora ; Holubová, Jana (advisor) ; Seydlová, Gabriela (referee)
Bordetella pertussis is a strictly human pathogen colonizing the upper respiratory tract, causing a respiratory disease known as whooping cough or pertussis. The introduction of whole-cell vaccines and acellular vaccines, resulted in a significant reduction in the incidence of disease and reduce the fatalities associated with infection. However, epidemiological data show a significant increase in the incidence of the disease in recent decades. The increasing incidence is mainly attributed to the transition from the whole- cell vaccine to an acellular vaccine. Based on research from recent years has shown that acellular vaccines have many drawbacks, and it is therefore necessary to change the vaccination strategy. One possible solution to the situation is the development of a new generation of whole-cell vaccines with reduced reactogenicity. The new whole-cell vaccine was prepared by a genetically modified B. pertussis strain. B. pertussis was modified using allelic exchange to develop strain encoding enzymatically inactive pertussis toxin, modified lipid A and lacking dermonecrotic toxin. This combination of genetic modifications in mice led to a decrease in reactogenicity test vaccine in vivo. In case of intranasal infection whole-cell vaccine containing genetically modified strain is providing...
Effect of surfactin on the lipid moiety of Bacillus subtilis cytoplasmic membrane
Sklenářová, Petra ; Seydlová, Gabriela (advisor) ; Lichá, Irena (referee)
Surfactin, a secondary metabolite produced by Bacillus subtilis, is a surface active compound and antibiotic permeabilizing membrane bilayer. The aim of this study was to reveal the self-resistance strategy at the level of the lipid moiety of cytoplasmic membrane, which B. subtilis employs to combat surfactin in concentrations that are lethal for other bacterial species. Non-producing strain B. subtilis 168 was cultivated in the presence of two different sublethal concentrations of surfactin (350 a 650 µg/ml), which was isolated from the culture broth of B. subtilis ATCC 21332. Presence of surfactin in the medium resulted in a concentration dependent lag phase, which took 40 min (350 µg/ml) and 3 h (650 µg/ml), respectively. Afterwards, the culture grew with the altered doubling time of 44 min (350 µg/ml) and 126 min (650 µg/ml), respectively. Surfactin induced substantial changes in the phospholipid composition of the cytoplasmic membrane. The proportion of the major phospholipid component phosphatidylglycerol decreased and inversely, the level of phosphatidylethanolamine increased. Interestingly, the content of phosphatidic acid rose considerably in the presence of surfactin concentration causing stimulation of B. subtilis growth (350 µg/ml). Liposome leakage assay using phospholipids mimicking...

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