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Bacterial REP elements: origins, variability and application.
Nunvář, Jaroslav ; Lichá, Irena (advisor) ; Pačes, Jan (referee) ; Melter, Oto (referee)
4 ABSTRACT (English) This thesis is based on three published research papers studying bacterial REP (repetitive extragenic palindrome) elements. REP elements are one of the best-characterized groups of bacterial DNA repeats, distributed mostly in gammaproteobacteria, including enterobacteria. They are present in noncoding parts of host genomes, usually occurring in hundreds of copies. REPs are typically aggregated in higher order repeats. In the Gram-negative model Escherichia coli, interactions of several proteins important for cell's physiology with REPs were described, indicating significant role for these elements for host cells. The first work (Nunvar et al. 2010) presents the discovery of a protein class, related to IS200/IS605 transposases. These proteins, termed RAYTs (REP-associated tyrosine transposases), contain characteristic motifs in their amino acid sequences, which are absent in canonical IS200/IS605 transposases. Another attribute of RAYTs is the arrangement of their encoding genes. These are single copy genes, always flanked at both termini by at least two REPs in inverted orientation. Based on the similarity between the REP-rayt-REP unit and insertion sequences of the IS200/IS605 family, between RAYTs and tyrosine transposases and between REPs and subterminal sequences of the IS200/IS605...
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Perspectives on the use of metabolic engineering in beta-lactam antibiotic biosyntheses
Pitkina, Anastasiya ; Kyslík, Pavel (advisor) ; Nunvář, Jaroslav (referee)
At present beta-lactams achieve leading positions among antibiotics as to the volume of sales and importance of utilization. This thesis compares selected industrially used chemical and enzymatic ways of production of beta-lactam antibiotics and further concentrates on the application of relatively novel approach of metabolic engineering in beta-lactam biosyntheses. Currently some of the described methods based on metabolic engineering are already being applied in production processes,whereas other technologies remain rather a theoretical possibility.
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Characterization of membrane pores formed by newly discovered colicin FY from Yersinia frederiksenii
Dolejšová, Tereza ; Fišer, Radovan (advisor) ; Nunvář, Jaroslav (referee)
Colicins are toxic exocellular proteins used by Gram-negative bacteria for interspecies and intraspecies competition. The colicin FY is a pore-forming protein which was recently discovered at Masaryk university. Kolicin FY is produced by strain Yersinia frederiksenii Y27601 and is active against other strains of genus Yersinia. By comparison of aminoacid sequences of C-terminal domains of selected colicins it was proved, that colicin FY is closely related to colicin Ib (Bosák et al., 2012). In this work I was trying to create brief and integrated summary about the group of colicins from the perspective of an outer membrane traslocation mechanism, overcoming the periplasmic space up to isertion of C-terminal colicin domain into the inner membrane phospholipid bilayer. Other aim of my work was to generally summarize pore properties of known colicins and compare them with recently measured characteristics of colicin FY. Keywords: colicin, Yersinia, planar lipid membranes, membrane pore
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Effect of environmental stresses on mutability of Bacillus subtilis - role of mismatch-repair system
Nunvář, Jaroslav ; Lichá, Irena (advisor) ; Konopásek, Ivo (referee)
The everchanging nature of bacterial environment requires adaptation to emerging novel conditions. One proposed way of adaptation involves increased generation of genetic variability in response to harmful conditions - a phenomenon called adaptive mutagenesis. However, the details of mechanisms of adaptive mutagenesis, and even its very existence, are far from clear. Our goal was to subject the Gram-positive model bacterium Bacillus subtilis to variety of environmental stresses, examine the rate of mutagenesis occuring and compare it to unstressed conditions. Next we wondered if there was a role for mismatch-repair system (MMR), the major pathway for mutation avoidance, in these processes. To accomplish this, we constructed systems to monitor the expression of MMR components both on transcription and translation level. We also developed a mathematical model for precise mutation rate determination in order to quantify the intensity of mutagenic processes. The monitoring of MMR proteins translation failed due to high background endogenous fluorescence present in B. subtilis cells. However, we found out, using transcription reporter system, that the expression of MMR is not influenced by imposition of harsh hyperosmotic shock upon cells. The expression of MMR was also barely influenced by nutrient limitation...
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