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Yeasts as a tool for study of cation homeostasis in eukaryotic cells
Farbulová, Michaela ; Zimmermannová, Olga (advisor) ; Zahumenský, Jakub (referee)
One of the key abilities of cells is to maintain a balance in the internal environment when the external surroundings change. Among the cations that have an irreplaceable role in living organisms are K+ , Na+ and H+ . In yeasts, most proteins transporting monovalent cations across cell membranes have been identified, making them an ideal model organism for studying cellular physiological processes in eukaryotic cells, including the principles of maintaining monovalent cation homeostasis. Using a unicellular organism such as yeast, we can also characterise proteins from phylogenetically higher organisms and humans, thus revealing disorders of transport systems related to pathological diseases. This bachelor thesis aims to point out the importance of yeasts in the research of the structure and function of cation transporters from eukaryotic cells and, at the same time, summarise knowledge about diseases associated with the disruption of the functions of individual cation transporters.
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Role of the Erv14 protein in the maintenance of alkali-metal-cation homeostasis in the yeast Saccharomyces cerevisiae
Hrášková, Michaela ; Papoušková, Klára (advisor) ; Vopálenská, Irena (referee)
The Erv14 protein works as a cargo receptor in the COPII vesicles. Many proteins, including Na+, K+/H+ antiporter Nha1, which participates in the maintenance of cell alkali-metal-cation homeostasis, need Erv14 for their trafficking from the ER. When Erv14 is missing, the Nha1 antiporter is partially retained in the ER and its overall transport activity is affected. Although Erv14 interacts with the antiporter through Nha1's transmembrane domains, a shortened version of Nha1 lacking its long hydrophilic C-terminus does not require Erv14 for its efficient trafficking to plasma membrane. This thesis contributes to the understanding of the role of the Erv14 protein in the maintenance of alkali-metal-cation homeostasis in S. cerevisiae cells. Two S. cerevisiae strains lacking ERV14 gene were prepared and the effect of this deletion on the growth and salt tolerance of cells was studied. Using heterologous expression of NHA antiporters from various yeast species with variable lengths of their hydrophilic C-termini we studied localisation and function of these antiporters in S. cerevisiae cells in the presence and in the absence of Erv14 protein. Our results suggested that the length of the antiporter's C-terminus might play a role in its requirement of Erv14 presence for its trafficking through the...
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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...
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