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Functional characterization of plant EXO70 exocyst subunit isoforms and their membrane targeting mechanisms
Sekereš, Juraj ; Potocký, Martin (advisor) ; Jaillais, Yvon (referee) ; Ischebeck, Till (referee)
Vesicle tethering complex exocyst is one of the key regulators of the cell polarity and morphogenesis in eukaryotes. The complex interacts with the secretory vesicle, as well as plasma membrane, and facilitates formation of cis SNARE complex leading into fusion of the vesicle with target destination. Two of the eight exocyst subunits, the SEC3 and EXO70 are known to bind plasma membrane via protein and lipid interactors in Opisthokont model organisms. Genomes of angiosperm plants encode a surprisingly wide repertoire of EXO70 isoforms with over 20 present in both Arabidopsis and diploid tobacco genome. It has been proposed that different EXO70 isoforms would form parts of functionally distinct subtypes of the plant exocyst complex driving membrane trafficking to various membrane domains. Specific interactions of peripheral membrane proteins with particular membrane phospholipids largely contribute to targeting of cellular components to subcellular compartments and membrane domains. This thesis focuses on role of protein-lipid interactions in regulation of plant cell polarity and contributes to functional analysis of the plant EXO70 family diversity. We introduce the topic with the theoretical reviews summarizing role of protein-lipid interactions in establishing plant cell membrane domains at...
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Study of selected plant exocyst subunits and its interactors in autophagy pathway.
Rácová, Denisa ; Žárský, Viktor (advisor) ; Wilhelmová, Naďa (referee)
Exocyst is a binding protein complex, which is evolutionary conserved in yeast, animal and in plant cells. It has crucial role in regulation of cell morfogenesis and cell polarity. The function of the exocyst complex is binding of secretoric vesicle to the proper side on plasma membrane in penultimate step of exocytosis. This process is essecial for function and survival of cell. Another process crucial for the cell is autophagy. In plants autophagy plays important role in the responses to nutrient starvation, senescence, abiotic and biotic stress. RabG3b are small GTPases, which have positive role in autophagy. In this work I described the interaction between RabG3b and some of subunits of exocyst complex: Exo70B1, Exo70B2 and Exo84b. I also studied changes in morfogenesis of tonoplast by induction and inhibition of authophagy and induction of anthocyans synthesis in Arabidopsis thaliana.
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Study of selected plant exocyst subunits and its interactors in autophagy pathway.
Rácová, Denisa ; Žárský, Viktor (advisor) ; Wilhelmová, Naďa (referee)
Exocyst is a binding protein complex, which is evolutionary conserved in yeast, animal and in plant cells. It has crucial role in regulation of cell morfogenesis and cell polarity. The function of the exocyst complex is binding of secretoric vesicle to the proper side on plasma membrane in penultimate step of exocytosis. This process is essecial for function and survival of cell. Another process crucial for the cell is autophagy. In plants autophagy plays important role in the responses to nutrient starvation, senescence, abiotic and biotic stress. RabG3b are small GTPases, which have positive role in autophagy. In this work I described the interaction between RabG3b and some of subunits of exocyst complex: Exo70B1, Exo70B2 and Exo84b. I also studied changes in morfogenesis of tonoplast by induction and inhibition of authophagy and induction of anthocyans synthesis in Arabidopsis thaliana.
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Structure- and sequence-based identification of functionally important amino acids in a protein family
Peclinovská, Iveta ; Novotný, Marian (advisor) ; Pleskot, Roman (referee)
A group of small GTPases consist of over twenty protein families in the super class P-loop. It has a very diverse cell functions. Small GTPases regulate the formation of vesicular follicles, cytoskeleton and nuclear transport. They participate also on cell proliferation and signaling. The aim of my work is to find important amino acids that define family and distinguish each other. I focus on families Arf, Rab, Ran, Ras and Rho. At the Rho family I am also devoted to classes Rho, Rac and Cdc42. Amino acids are identified using bioinformatic programs selected Consurf and Sca5. The objective is also to test P2RANK specialized tool developed at the Charles University in Prague that predict ligand binding sites from protein structure in different families. Founding amino acids can have a big role in the functional divergence of individual families and classes of small GTPases and can be the basis for future study example for the proliferation of cancerous cells. 1.1 Keywords Powered by TCPDF (www.tcpdf.org)
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Are there any sequence determinants of functional divergence of GTPases?
Kraus, Ondřej ; Novotný, Marian (advisor) ; Potocký, Martin (referee)
Small GTPases are important proteins that affect many cellular processes. In my work I compare the five most important protein families of small GTPases - Arf, Rab, Ran, Ras and Rho to identify amino acids responsible for major functional differences between different protein families. To compare them, I have used the structural data from the PDB database and sequences from the UniProt database. I have discovered previously undescribed groups of amino acids specific for each protein family of small GTPases with the help of programs ConSurf and Sca5. I also carried out a pilot study of the applicability of B-factors as indicators of bond strength in the protein structure on the example of small GTPases. The first results are not entirely conclusive, but they do not exclude the applicability of B-factors as indicators of bond strength either. Powered by TCPDF (www.tcpdf.org)
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Role of GIT-PIX signaling cassette in cytoskeleton regulation
Beránek, Karel ; Dráber, Pavel (advisor) ; Libusová, Lenka (referee)
4 Abstract The cytoskeleton is a cellular structure comprised of three types of protein filaments called microfilaments, intermediate filaments and microtubules respectively. These filaments are highly dynamic and can change their organisation and properties according to the current needs of a cell. This system of cytoskeletal polymers is regulated by a plethora of interacting proteins, among which belong the GIT proteins. GIT proteins contain a great amount of interaction domains, and they form oligomers which function as a scaffold for the binding of associated proteins. In this way they facilitate specific subcellular localisation of many proteins and their complexes. GIT proteins contain a catalytic ARF-GAP domain that regulates the function of ARF GTPases. GIT proteins interact with PIX proteins. These proteins function as GEFs for Rho GTPases and thus regulate signal transduction influencing the cytoskeleton. GIT and PIX interact with each other by the means of their coiled-coil domains and form complexes called "GIT-PIX signalling cassettes". The cassettes regulates mostly microfilaments during the establishment of cell polarity, formation of membrane protrusions, and in cell motility and adhesion. Results of experiments published in the last few years suggest that the GIT-PIX signalling cassette...
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