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Analysis of essentiality of glmM gene coding for phosphoglucosamine mutase of Streptococcus pneumoniae.
Krupička, Jiří ; Branny, Pavel (advisor) ; Čáp, Michal (referee)
Phosphoglucosamine mutase (GlmM) is an enzyme of bacterial cell wall biosynthesis. The main aim of this thesis was to find out, whether gene glmM is essential for viability of Streptococcus pneumoniae. Therefore, we prepared merodiploid strain containing two copies of glmM; the genomic gene and ectopic copy under control of zinc inducible promoter. Subsequently, depletion strain was prepared by deletion of genomic copy of glmM. This strain was further used for analysis of viability and phenotype features in the medium containing various concentrations of zinc ions, an inducer of ectopic glmM expression. We found out, that the viability of this strain was strictly dependent on the concentration of inducer and further, that depletion of GlmM resulted in remarkable morphological defects. The rescue of mutant strain was observed after addition of inducer up to the level of the control sample. These results have provided the evidence of glmM essentiality for S. pneumoniae viability. Furthermore, we analyzed, whether phosphorylation of key amino acid residues, S99 and S101, is essential for GlmM functionality. Four different strains were prepared by means of site-directed mutagenesis expressing glmM with substitutions of key serine residues for alanine or glutamic acid. Since deletion of chromosomal locus in...
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Role of variable chains at the interface between subunits in forming ATP-binding pocket and function of P2X4 receptor
Tvrdoňová, Vendula ; Zemková, Hana (advisor) ; Novotný, Jiří (referee) ; Vlachová, Viktorie (referee)
7 ABSTRACT Crystallization of the zebrafish P2X4 receptor in both open and closed states revealed conformational differences in the ectodomain structures, including the dorsal fin and left flipper domains. The role of these domains in forming of ATP-binding pocket and receptor function was investigated by using alanine scanning mutagenesis of the R203- L214 (dorsal fin) and the D280-N293 (left flipper) sequences of the rat P2X4 receptor and by examination of the responsiveness to ATP and orthosteric analog agonists 2- (methylthio)adenosine 5'-triphosphate, adenosine 5'-(γ-thio)triphosphate, 2'(3'-O-(4- benzoylbenzoyl)adenosine 5'-triphosphate, and α,β-methyleneadenosine 5'- triphosphate. ATP potency/efficacy was reduced in 15 out of 26 alanine mutants. The R203A, N204A, and N293A mutants were essentially non-functional, but receptor function was restored by ivermectin, an allosteric modulator. The I205A, T210A, L214A, P290A, G291A, and Y292A mutants exhibited significant changes in the responsiveness to orthosteric analog agonists. In contrast, the responsiveness of L206A, N208A, D280A, T281A, R282A, and H286A mutants to analog agonists was comparable to that of the wild type receptor. These experiments, together with homology modeling, indicate that residues of the first group located in the upper part of...
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Study of red yeast metabolism on molecular level
Roubalová, Monika ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
This master thesis is focused on the molecular characterization of the eight red yeasts species. For molecular characterisation, the most variable rDNA regions ITS1, 5,8S ITS2 and the region encoding the large ribosomal subunit (26S) were amplified. This long region of the yeasts DNA was sequenced and compared by NCBI database for identification. The red yeasts identification was confirmed by data from DGGE method. Another aim of this thesis was to select the best yeasts producer of carotenoids and triacylglycerols. Rhodosporidium toruloides was found as the best producer and, thus, this strain was subjected to random mutagenesis by UV irradiation. The results of the production of metabolites by R. toruloides were compared with mutant strains, which were also adapted to the glycerol and waste whey substrates. The mutant strain G33 was found as the best producer of total carotenoids with a yield of 7.14 mg.g-1 of biomass. The highest production of ergosterol was demonstrated by the mutant strain Y34, the ergosterol yield was 47.72 mg.g-1 of biomass. The wild type of R. toruloides was able to produce the highest amount of both carotene (2.42 mg.g-1 of biomass) and TAG (76.32 mg.g-1 of biomass) on glucose medium.
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Cloning, expression and characterization of human serine racemase mutants
Nováková, Ilona ; Brynda, Jiří (referee) ; Konvalinka, Jan (advisor)
AAbbssttrraacctt Human serine racemase (hSR) is a cytosolic pyridoxal-5'-phosphate dependent enzyme localized in the central nervous system. It synthesizes D-serine, which is an endogenous coagonist for the N-methyl-D-aspartate (NMDA) receptors and plays a key role in excitatory neurotransmission in the brain. Thus, human serine racemase is a promising target for the treatment of neurodegenerative diseases connected with NMDA receptors. However, few specific inhibitors have been identified to date and the crystal structure of hSR has become available only very recently. We decided to perform a random mutagenesis to determine the amino acid residues critical for the enzyme activity. Ser 84 was reported as a catalytic residue along with Lys 56. After analysis of a double mutant S84G/P111L which retained its capability to convert L-serine to pyruvate, we prepared and characterized the single mutant S84G in order to exclude potential effect of the P111L mutation.on the activity of the analyzed enzyme. KKeeyy wwoorrddss:: D-serine; Serine racemase; PLP-dependent enzymes; Random mutagenesis; Racemases
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Use of Waste Substrates to Production of Enriched Yeast Biomass
Starečková, Terezie ; Demnerová, Kateřina (referee) ; Vávrová, Milada (referee) ; doc.PharmDr.Petr Babula, Ph.D. (referee) ; Márová, Ivana (advisor)
Yeasts are like other organisms constantly exposed to environmental influences. Their survival depends on the skills to adapt to environmental changes, including the ability to use various alternative sources of nutrients. In presented PhD thesis carotenogenic yeast belonging to the genera Rhodotorula, Sporobolomyces and Cystofilobasidium were tested for ability to use of selected waste substrates, and also subjected to several types of exogenous stress effects and mutations in order to increase the production of microbial biomass enriched with specific metabolites. As alternative nutrient sources derived from waste substrates from agricultural and farm production apple peel, pulp, corn germ and more were tested. Yeasts were also exposed to osmotic, oxidative and combined stress (benefits of various concentrations of NaCl and H2O2 to the culture media), followed by metal ions of selenium and chromium in concentrations of 0.01 mM, 0.1 mM and 1 mM. The effect of mutagen methanesulfonic acid ethyl ester was tested too. In all experiments the adaptivity of cells, morphological changes, color pigments produced by the media while some important fungal metabolites production and changes in chromosomal DNA fragmentation were analyzed. In order to evaluate potential changes in the yeast genome after treatment with mutagen and stress factors methods for isolation of intact chromosomal DNA and DNA analysis by pulsed field gel electrophoresis was optimized. The amount of produced metabolites was mainly analyzed by RP-HPLC with UV/VIS and MS detection. The work has been shown that most strains are able to use waste substrates and produced selected target metabolites. Biomass, for example, in R. aurantiaca on apple fiber was about 7 g/l and in C. capitatum cultivated on modified whey reached to 9 g/l. Amount of produced carotenoids by R. aurantiaca cultivated on wheat germ and maize after enzymatic hydrolysis by F. solani was 1.01 mg/g and S. roseus on pasta 4.3 mg/g. The values of ergosterol synthesis in R. aurantiaca are on the apple shells around 4.8 mg/g, in S. roseus on pasta with the enzymatic hydrolysis of P. chrysosporium 8.9 mg/g. The best substrate for biomass production and induction of carotenoids are waste substartes containing a mixture of simple and complex carbohydrates enriched with the addition of nitrogen compounds. Potential cytotoxic effect of stress factors of low concentrations was demonstrated. Red yeast genome was able to distribute by optimized PFGE, the karyotype of tested yeasts contain 11 or more chromosomes with visible differences between yeast species and genera. During exchange internship the ability of recombinant yeast S. cerevisiae to convert xylose to xylitol, which would be achieved by increasing the production of bioethanol as alternative fuel sources was studied. It turned out that both ligninocellulose materials to bioethanol production, as well as various waste substrates for microbial synthesis of carotenoids would reduce costs for industrial production of yeast metabolites, as well as to reduce the negative burden on the environment.
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