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The effect of HAc1p on the development of yeast colony
Maršíková, Jana ; Schierová, Michaela (advisor) ; Pichová, Iva (referee)
On solid surfaces wild strains of Saccharomyces cerevisiae form biofilm-like, structured colonies enabling them to survive long-term in hostile environments in the wild. However, the molecular mechanisms underlying the spatio-temporal development of colonies and their resistance to hostile conditions are still largely unknown. In this study, we analyzed the effect of the HAC1 gene on the colony morphology of wild strains of S. cerevisiae. The transcription factor Hac1p activates the unfolded protein response (UPR), which leads to activation of the expression of genes encoding components of the protein secretory pathway, and genes involved in stress responses in the endoplasmic reticulum (ER). The impact of HAC1 deletion is significant even under non-stress conditions and causes a radical reduction of structured colony architecture in hac1∆ strains derived from two wild S. cerevisiae strains (PORT and BR-F-Flo11p-GFP) and one laboratory ΣSh strain forming semi-fluffy or fluffy colonies. The hac1∆ strains exhibit a decreased vegetative growth rate, reduced cell attachment to the agar and an ineffective cell-cell adhesion resulting in decreased flocculation. The hac1∆ strains derived from BR-F-Flo11p-GFP contain a low level of Flo11p surface adhesin which is considered very important for the proper...
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The function of Pmp3p protein
Belovičová, Martina ; Palková, Zdena (advisor) ; Pichová, Iva (referee)
During development of Saccharomyces cerevisiae colonies on solid substrate, metabolic transitions occur, which are reflected by pH changes around the colony and also by changes in cell membrane potential. Analyses of transmemebrane potential oscillations revealed a function for Plasma Membrane Proteolipid 3 (Pmp3p) in this process. The thesis discusses possible function of Pmp3p protein mainly on the basis of direct observation of Pmp3p localization in vivo under variety of cultivation conditions. Yeast strains with different variants of Pmp3p protein fused with different protein tags that allow monitoring of Pmp3p localization and concentration in cells were prepared by homologous recombination. Localization of Pmp3p in the plasma membrane and in lipid particles was found. The Pmp3p level in cells was stable during development of colonies growing on either respirative or fermentative carbon source medium. High concentration of extracellular sodium chloride did not evoke increase in Pmp3p-GFP concentration. Key words: Pmp3p, proteolipids, UPF0057 (PMP3) family, Saccharomyces cerevisiae, long term survival, lipid particles
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Differentiation in Saccharomyces cerevisiae colonies
Čáp, Michal ; Palková, Zdena (advisor) ; Pichová, Iva (referee) ; Demnerová, Kateřina (referee)
Yeast colonies are, alongside to bacterial biofilms, multicellular communities formed by unicellular microorganisms. These specific communities differ in many ways from populations cultivated in planktonic cultivations. Gradients of nutrients, metabolic by- products and other factors are formed and preserved within these structures, which provides a basis for cellular differentiation. Current literature concerning these issues with emphasis on yeast colonies and biofilms is summarised in the Introduction of this work. Section Results then describes my contribution to the knowledge on the differentiation of the colonies of Saccharomyces cerevisiae as a model system for studying microbial multicellular structures. Previously described horizontal differentiation, i.e. differentiation between colony centre and margin, is further characterised with respect to ammonia signalling and stress resistance. The importance of genes conferring the cell`s oxidative stress resistance in colony differentiation was studied and it was concluded that not stress resistance but rather metabolic and other changes promoted by ammonia signal are important for colony differentiation and survival. A new type of colony differentiation - the horizontal, i.e. differentiation between upper and lower part of the colony, is...
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EF-Tu PROTEIN DOMAINS Functions and Thermostability
Šanderová, Hana ; Jonák, Jiří (advisor) ; Pichová, Iva (referee) ; Mikulík, Karel (referee)
6 % The bacterial elongation factor Tu (EF-Tu) has been extensively studied for decades as it plays a key role in protein biosynthesis. It is a model, multifunctional GTP-protein. This protein is also in the centre of interest as a possible target for new antibiotics. Moreover, the high homology in structure and function makes EF-Tu proteins suitable for the studies of evolutionary relationships between organisms and for elucidation of the structural features of adaptation to various living conditions. Furthermore, since all known EF-Tu proteins are composed of three distinct domains, they can also serve as suitable models for the understanding of domain organization in proteins. One of the main research projects of the Department of Gene Expression at the Institute of Molecular Genetics AS CR, where I did my PhD studies, was the study of the primary structure, transcription regulation and functions of bacterial elongation factors Tu from Gram positive thermophilic bacterium Bacillus stearothermophilus and from Gram negative mesophilic bacterium Escherichia coli. In this work, we focused on the structure-function relationships between EF-Tu proteins and their domains. The domain effect had been before our studies tested mainly by truncated EF-Tu forms lacking one or two domains. In contrast, we decided to...
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Differentiation of yeast colonies and development of new approaches to monitor oxygen and nutrient availability
Vopálenská, Irena ; Janderová, Blanka (advisor) ; Demnerová, Kateřina (referee) ; Pichová, Iva (referee)
Yeast Saccharomyces cerevisiae as an unicellular organism is one of the best-studied experimental organisms. It is an important model organism for the study of intracellular processes of eukaryotic cells. Yeasts are also social organisms with cell-to-cell communication able to form organized multicellular structures (colonies and biofilms). Yeast and other microorganisms in nature prefer to form colonies on solid substrates rather than to grow as "planktonic" single cells (Palková, 2004; Wimpenny, 2009). The yeast S. cerevisiae typically forms colonies, biofilms were described only rarely. Yeast colonies exhibit an organized morphological pattern characteristic of each particular yeast strain (Kocková-Kratochvílová, 1982). This work is focusing on morphology and differentiation of the S. cerevisiae colonies of common laboratory strains forming less structured colonies, and strains of the Σ1278b genetic background forming highly structured "fluffy" colonies. It shows that polarized budding pattern and especially cell ability to form aggregates enable development of structured morphology. During development of "fluffy" colonies two differently regulated events of dimorphic switch from yeast form to filamentous growth occur. One of these events is dependent on the surface glycoprotein, Flo11p flocculin. This...
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