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Heat-shock protein 90 (HSP90) in cell physiology.
Karmazin, Alina ; Bařinka, Cyril (advisor) ; Pavlíček, Jiří (referee)
Heat-shock protein 90 (HSP90) is a molecular chaperone that represents one of the most important proteins for cellular homeostasis in all life domains. Chaperones are proteins that assist other proteins in proper folding and refolding. First discovered as a protein of a heat-shock response, HSP90 eventually emerged as a hub connecting multiple cellular functions, such as transcription, translation, DNA repair, immune response, cell signaling, etc. Unsurprisingly, HSP90 also plays a role in the pathogenesis of human diseases: various cancers, and neurodegenerative and respiratory diseases. For that reason, it became a target of medical research. HSP90 is a homodimer consisting of two protomers, each of which is composed of three domains: N-terminal domain, middle domain, and C-terminal domain. To fulfill its functions, HSP90 goes through an ATP-dependent conformational cycle, tightly regulated by a large group of assisting proteins-co-chaperones, and several post-translational modifications, such as phosphorylation and acetylation. Acetylation is known to affect HSP90 binding to nucleotides, clients, and co-chaperones, and thus it is suggested as a control mechanism of HSP90 function. Potentially, HSP90 acetylation can be utilized in the treatment of hormone-dependent cancers. Therefore, regulators of HSP90...
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Prions in yeast
Bezdíčka, Martin ; Palková, Zdena (advisor) ; Žíla, Vojtěch (referee)
The thesis describes yeast prions and their biological effects on yeast in general. It defines the basic characteristics of yeast prions, that distinguish prions from other proteins. The thesis introduces various possibilities of prion formation, and propagation as well as specific types of yeast prions, including various functions of most studied types of prions. The thesis also focuses on chaperones that affect the state of yeast prions in cells. Lastly, the thesis indicates similarities between yeast prions and mammalian prions that are related to neurodegenerative diseases. Key words: Yeast prions, features of yeast prions, chaperones, neurodegenerative disease, Saccharomyces cerevisiae
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Role of molecular chaperones Hsp70 and Hsp90 in the replication cycle of DNA viruses
Žáčková, Sandra ; Horníková, Lenka (advisor) ; Poláková, Ingrid (referee)
Molecular chaperones are proteins which enable other proteins to assemble into native conformation and are essential for viability of the cells. Chaperones of the Hsp70 family bind to newly synthetized and denaturated proteins, prevent their aggregation and facilitate their assembly. They participate in assembly and disassembly of oligomers and also in the transport across the membranes. Chaperones of the Hsp90 family do not participate in the assembly of nascent or denaturated proteins. They bind proteins which are nearly in native conformation and enable them to assemble into conformation suitable for ligand binding or interacting with other proteins. These attributes predestinate chaperones to participate in the replication cycle of DNA viruses. A huge amount of proteins is translated during viral infection. These proteins require the chaperones to facilitate their assembly and are also required for assembly into oligomers and macromolecular structures. In addition to capsid assembly the chaperones also participate in transport of genetic information to the sites of replication, disassembly of incoming viral particles or replication of viral DNA. Therefore, the development of specific chaperone inhibitors is a promising approach. They could be used against broad spectrum of viral infections...
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Prions in yeast
Bezdíčka, Martin ; Palková, Zdena (advisor) ; Žíla, Vojtěch (referee)
The thesis describes yeast prions and their biological effects on yeast in general. It defines the basic characteristics of yeast prions, that distinguish prions from other proteins. The thesis introduces various possibilities of prion formation, and propagation as well as specific types of yeast prions, including various functions of most studied types of prions. The thesis also focuses on chaperones that affect the state of yeast prions in cells. Lastly, the thesis indicates similarities between yeast prions and mammalian prions that are related to neurodegenerative diseases. Key words: Yeast prions, features of yeast prions, chaperones, neurodegenerative disease, Saccharomyces cerevisiae
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The effect of heat shock stress on enzyme activities in plants.
Doričová, Vlasta ; Hýsková, Veronika (advisor) ; Liberda, Jiří (referee)
Heat stress is one of abiotic stress factors, which fundamentally influences the growth and development of plants. Plants response to heat stress by series of cell and metabolic changes, the specificity of heat stress is synthesis of molecular chaperons, called heat- shock proteins (HSP). The influence of heat shock (in the form of 1 hour application of 40řC from 20řC) on the activity of NADP-dependent enzymes, enzymes of Hatch-Slack cycle, glycosidases and the activity of peroxidase in tobacco plants (Nicotiana tabacum L. cv. Petit Havana SR1) was studied in this work. Since HSP are involved in proper folding of immature, misfolded or partly denaturated proteins, in degradation of denaturated proteins and in induction of thermotolerance of plants, the aim of this work was to find out, if the activity of studied enzymes will be maintained or modulated within the plant defense response. The highest amount of HSP70 detected immunochemically together with higher activities of NADP-malic enzyme, phosphoenolpyruvate carboxylase, β-hexosaminidase and α- mannosidase compared to control plants was found 1 hour after application of heat shock. Peroxidase activity was most increased 1 day after HS compared to controls. Using native electrophoresis the differences in isoform content between control and...
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