National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
The role of plasma membrane Na+/H+ antiporters in the physiology of yeast cells
Papoušková, Klára ; Sychrová, Hana (advisor) ; Hašek, Jiří (referee) ; Flachs, Pavel (referee)
) r Nhal-type antiporterswith differentsubstratespeciÍicity(or affinityto individualsubstrates) andfunctions.One of themis involvedin thedetoxificationof cells andtheothercouldplay an importantrole in the maintenanceof stableintracellularpotassiumcontent,cell volume andpH of thecýoplasmthanlsto its abilitytotransportK+. At this time, no yeast speciespossessingsolely a Na*/fI*antiporterwith narrow substratespecificity (for Na* and Li) is known;therefore,the physiologicalrole of Nhal- type antiportersseemsto be complexwith a participationboth in the eliminationof toxic cationsfromcells andin themaintenanceof stableintracellularK* concentration,cell volume andcýoplasmic pH. 4.Summary Themainresultsof thethesíscanbesummarizedas: o The studiesof sequencesof yeastalkali metalcation/Iťantiporters(Nhal, Nhxl andKhal families)in silico showedthatthe structureof all threegroupsof theseproteinsprobably contains 12 transmembranesegments,we found some conservedamino acid residuesor motifslikely to be importantforproperfunctioningof antiporters,andourphylogeneticstudy revealedthatNhxl proteinsare relatedto both plant and mammalianNa*/Iť antiporters, Khal antiportersare close to thebacterialrelativesandNhal-type proteinsform a soparate goup so far characteizedonly in yeastsor fungi. o The D. hanseniiNHAI geneencodesa...
Heat-induced stress granules of Saccharomyces cerevisiae.
Groušl, Tomáš ; Hašek, Jiří (advisor) ; Janderová, Blanka (referee) ; Sychrová, Hana (referee)
(English) In response to environmental stresses, cells try to adapt to changed living conditions. Regulation of translation process provides fast-responding and versatile system enabling execution of stress-induced expression program. Messenger ribonucleoprotein complexes (mRNPs) engaged in translation and mRNA turnover are remodelled and may accumulate into higher-order assemblies, in connection to stress-induced translational changes. Stress granules (SGs) and processing bodies (PBs) are examples of such assemblies. Through them, further fate of mRNA molecules and certain translation machinery components is determined. In an effort to better understand the entire role of SGs in cellular metabolism, we performed the analysis of heat-induced SGs in model organism Saccharomyces cerevisiae. We contributed to the finding that SGs phenomenon is evolutionary conserved in eukaryotic kingdom proving that SGs are formed also in unicellular yeast S. cerevisiae under robust heat stress. The SGs reassemble their counterparts from higher eukaryotes in core composition and proposed functions. However, they possess also unique nature, which seems to be specific to the yeast. We further extended the data about heat-induced SGs, with a focus on additional composition, dynamics, associated proteins and a relation...
Biochemical and molecular basis of specific properties of non-conventional osmotolerant yeast
Dušková, Michala ; Sychrová, Hana (advisor) ; Malcová, Ivana (referee) ; Janderová, Blanka (referee)
Unicellular organisms such as yeasts are permanently exposed to environmental changes, especially to changes of the concentration of osmotically active substances. Yeast species, which are able to cope with these changes properly, are called osmotolerant (Zygosaccharomyces rouxii, Pichia sorbitophila, Debaryomyces hansenii, etc.). The osmotolerance of yeasts depends on many physiological parameters but the most important is the efficient metabolism of internal osmolytes. This role is played by the small molecule of glycerol in most yeast species. Yeasts have to release the surplus of glycerol during the hypoosmotic shock. On the other hand, the hyperosmotic conditions require synthesis and accumulation of this small compound in a high quantity. The model yeast Saccharomyces cerevisiae has two systems transporting glycerol. First of them is the ScFps1 channel which is important mainly for releasing of glycerol during hypoosmotic shock. The second transporter, called ScStl1, is employed in accumulation of glycerol in case of hyperosmotic conditions. Detailed study of physiological properties of the three above mentioned species was performed within this work. Although they do not differ in basic morphological parameters from S. cerevisiae, their difference lies in the ability to survive desiccation,...
Physiological role of Na+/H+ antiporters in yeast cells
Zahrádka, Jaromír ; Sychrová, Hana (advisor) ; Obšilová, Veronika (referee) ; Pichová, Iva (referee)
3 Abstract Yeast Saccharomyces cerevisiae belongs to important models for alkali-metal-cation homeostasis research. As other cells, certain intracellular content of K+ is necessary for S. cerevisiae, but Na+ or other alkali metal cations (Li+ , Rb+ ) are toxic for yeast cells. Uniporters Trk1 and Trk2 are responsible for K+ accumulation, while efflux of Na+ , Li+ , Rb+ and K+ is ensured by Ena ATPases, Na+ (K+ )/H+ antiporter Nha1 and K+ specific channel Tok1. Several regulators of K+ (Na+ ) transporters are already known, but reciprocal regulation between transporters and overall picture of the maintenance of alkali-metal-cation homeostasis is still unclear. In this work, K+ circulation (simultaneous uptake and export of K+ ) was shown to be important in alkali-metal-cation homeostasis maintenance. K+ circulation is maintained using reciprocal regulation and interactions between K+ exporters and importers. Though obtained results showed that the alkali-metal-cation homeostasis and associated physiological parameters (e.g. membrane potential, cell size, salt sensitivity) are strain specific, Nha1p was verified to be important for cell survival in ever-changing natural environment. Furthermore, two novel positive regulators of Nha1p activity were found, 14-3-3 proteins and Cka1 kinase. 14-3-3 proteins...
Characterization and functional analysis of IST2 gene in yeast Saccharomyces cerevisiae.
Andršová, Markéta ; Sychrová, Hana (advisor) ; Hlaváček, Otakar (referee)
IST2 is known as a gene encoding in the model yeast Saccharomyces cerevisiae a membrane protein, that is studied thanks to a unique way of biogenesis and trafficking that apparently does not use classical secretory pathway. Although the gene was named more than ten years ago according to the phenotype of cells with its deletion (Increased Sodium Tolerance), the role of this protein in cell tolerance to toxic sodium has not been elucidated. Our searches in databases revealed that similar proteins are encoded in the genomes of other species of yeast, but none of them has been studied so far. In this work, four new strains lacking IST2 have been constructed in the genetic backgrounds differing by the presence of genes encoding transport systems for accumulation of potassium (Trk1, Trk2), for export of surplus potassium cations (Tok1, Ena1-5, Nha1) and for export of toxic cations lithium and sodium (Ena1-5, Nha1). Plasmid carrying the gene coding IST2 sequence has also been conctructed. The effect of IST2 deletion in different genetic backgrounds was studied by phenotypic tests on solid and liquid media. It was found that IST2 probably does not play a role in osmotolerance in general (absence of the phenotype of IST2 deletion on high concentrations of KCl), but its presence affects ability of the cells...
Study of mechanisms of ammonia production in yeast colonies and liquid cultures
Strachotová, Dita ; Váchová, Libuše (advisor) ; Sychrová, Hana (referee) ; Gášková, Dana (referee)
Yeast, although non-motile and unicellular organisms can create organized structures, colonies, in which cells communicate and cooperate and which in some ways resemble multicellular organisms. Our previous studies on yeast colony development revealed that colonies periodically change pH of their surroundings. Alkalization of an agar medium is accompanied by production of volatile ammonia that acts as the long-range signal. Microarray analysis of the expression changes in Saccharomyces cerevisiae colonies during their transition from acid to alkali phase revealed significant changes in yeast transcriptome. Among others, strong induction of expression of three homologous genes ATO1 (YNR010c, ADY2), ATO2 (YNR002c, FUN34) and ATO3 (YDR384c) at the beginning of the alkali phase was found. These genes encode membrane proteins that may function as ammonium/H+ antiporters. This work contributes to better understanding of both the ammonia signaling and the role of putative ammonium exporters - Ato proteins. It was revealed, that other volatile compounds - methylamine and propylamine - are (in addition to ammonia) able to induce entry into the alkali phase of yeast colony development. Moreover, the significant impact of the transport of monocarboxylic acids on ammonia production and yeast colony development...
Study of the performance of microbial MDR pumps by fluorescent probes: effect of potential inhibitors
Kodedová, Marie ; Gášková, Dana (advisor) ; Höfer, Milan (referee) ; Sychrová, Hana (referee)
The current increased use of antifungal agents has resulted in the development of resistance to these drugs. Search for new antifungals with different mechanisms of action overcoming the multidrug resistance is thus underway. Surface-active antifungals have the advantages of minimizing host toxicity and the emergence of drug resistance. We have developed a fluorescence method based on the use of the potentiometric fluorescent probe diS-C3(3), substrate of two major S. cerevisiae MDR pumps, Pdr5p and Snq2p. It allows us to monitor with high sensitivity and in real time changes in the activities of both pumps and also in membrane potential. We present here an efficient strategy for identifying pump inhibitors with minimal side effects on membrane integrity, and compare the potencies of different inhibitors towards MDR pumps. New efficient inhibitors of MDR pumps could potentially be used in conjunction with current antimicrobials that are MDR pump substrates. The method can be also used to determine the mechanism of action of surface-active drugs and their lowest effective concentrations.

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