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Plasma membrane - cell wall interactions - adhesion and signalling
Králíková, Dagmar ; Tylová, Edita (advisor) ; Krtková, Jana (referee)
Interaction of the cell wall and plasma membrane is essential for proper cell functioning as it affects, for example, cell growth, water relations or pathogen penetration, and provides protection against external factors. This interaction may take the form of signal exchange or component transport and its necessary prerequisite is the contact between the two structures. The contact is ensured not only by turgor pressure but also by their direct connection. Experimental evidences have long been known to show that this connection indeed exists - for example, Hechtian strands that are visible in the plasmolyzed cell. Another example is band plasmolysis in cells of the endodermis and exodermis with the Casparian strips, where the plasma membrane is still attached to the cell wall at the site of the strip. This attachment contributes to the protective feature of the apoplastic barrier and allows maintaining it even during plasmolysis. The anatomic aspects of the phenomenon have long been investigated, but specific proteins providing this interaction at the molecular level have not yet been experimentally confirmed. The aim of the bachelor thesis is to summarize recent findings about the mechanisms ensuring the physical connection (adhesion) between the plasma membrane and the cell wall in the plant...
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Searching for mechanisms and functions of microtubular interactions with other plant cell structures
Krtková, Jana ; Schwarzerová, Kateřina (advisor) ; Vaňková, Radomíra (referee) ; Ovečka, Miroslav (referee)
Microtubular cytoskeleton is involved in many processes in plant cells, including cell division, growth and development. Other proteins enable its functions by modulation of its dynamics and organization and by mediation of functional and structural interaction with other cell structures. Identification of the mediating proteins and the functions of these interactions under specific conditions were the main aims of the thesis. Membrane proteins interacting with microtubules were identified using biochemical methods. Surprisingly, the identified proteins co-sedimenting with microtubules were not members of the "classical" microtubule associated proteins (MAPs). There were enzymes, chaperones and plant specific proteins among them. For further studies, the identified microtubule-associated heat-shock protein 90 (Hsp90_MT) was chosen. Recombinant Hsp90_MT binds directly to microtubules and tubulin dimers in vitro. The ATP-binding pocket is not responsible for this association. In BY-2, Hsp90_MT co-localizes with phragmoplast and cortical microtubules and is involved in microtubule recovery after their depolymerization during cold treatment. In plants, Hsp90 is involved in cell cycle progression, its inhibition causes cell-cycle arrest in G1 phase. Based on literature search for animal proteins...
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Molecular base of plant HSP90-MT interaction
Benáková, Martina ; Krtková, Jana (advisor) ; Malcová, Ivana (referee)
Microtubules (MTs) are one of the essential cell structure that participate in a number of key events in the plant cells and their properties and functions are influenced and modified by many other proteins. These proteins belong to a group of microtubule- associated proteins (MAPs, microtubule-associated proteins). One of the MAPs, the molecular chaperone Hsp90, examines and fulfills a large number of different functions in the cell. Its colocalization with MTs has been demonstrated previously by Freudenreich and Nick (1998) and Petrášek et al. (1998). However, direct interaction with MTs was described only recently using cosedimentation assay. The specific cytosolic isoform of tobacco Hsp90 bound to MTs was called Hsp90_MT due to its ability to bind MTs. It has been also found that the binding to MTs is independent on the activity of ATP (Krtková et al., 2012). The authors also described a positive effect of Hsp90_MT on MT recovery after their exposure to cold stress. Although MT cytoskeleton dynamics is influenced by a large number of MAPs, it is surprising that the molecular mechanism of MAPs interaction with MTs and their MT-binding domains have not been described yet. Therefore, we decided to determine the tobacco Hsp90_MT MT-binding domain by production of a set of recombinant proteins...
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Advanced methods of endocytosis and exocytosis visualisation on plant cell membrane
Ortmannová, Jitka ; Fendrych, Matyáš (advisor) ; Krtková, Jana (referee)
Endocytosis and exocytosis participate in developmental program of plants.The ability to target exocytic vesicles to particular domains of plasma membrane is crucial for polarization, growth and development. Plasma membrane are recycled via various mechanisms of endocytosis which participates also in establishing plant cell polarity. To extend our knowledge of membrane transport it is essential to observe the activity of its components with high resolution in living cells of intact organisms in real time. Such methods belong mainly into the field of light microscopy and nanoscopy exceeding often diffraction limit (200 nm). Nanoscopic techniques like PALM, STORM, SIM, STED, offer multicoloured visualization of fluorophores and high resolution 3D reconstruction of cellular component. These methods have been used only sporadically in the field of plant biology but there should be no serious obstacles for they employment. The key words: clathrin, difraction limit, endocytosis, exocytosis, exocyst, fluorophore, plant cell, microscopy, resolution
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Microtubule-associated proteins in plants
Benáková, Martina ; Krtková, Jana (advisor) ; Vinopal, Stanislav (referee)
1. Abstract and key words MTs are one of the basic cellular protein structure. Their features and function are influenced and modified by group of other proteins, i.e. microtubule-associated proteins (MAPs). In the last decades, an extensive research on MAPs and their wide range of functions has been carried out. Therefore we are aware of the involvement of some of the MAPs in MT dynamics, other have been shown to have rather structural function. They bundle MTs with various cell structures, such as the other MTs, proteins, organelles, actin cytoskeleton or plasma membrane. Many described MAPs are homologous in the whole eukaryotic domain, for example MAP65 or EB1 (END BINDING 1) family, therefore it is interesting to follow if and how the functions of plant MAPs differ from their animal counterparts. On the other hand, there are many specific MAPs with unique functions in plants, e.g. ATK5 or SPR1 (SPIRAL 1). This Bachelor thesis is a survey on current knowledge of plant MAPs and it makes an effort to present their characteristic and functions in plant cell and organism. Key words: cytoskeleton, microtubules, microtubule-associated proteins, plant cell, growth and development
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