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The role of exocyst subunit AtEXO70E2 in autophagy and secretion
Moulík, Michal ; Sabol, Peter (advisor) ; Janda, Martin (referee)
Exocyst is a protein complex composed of eight subunits, evolutionarily conserved in yeasts, animals, and plants. The main function of exocyst is to mediate the tethering of secretory vesicles to the plasma membrane. However, the involvement of exocyst in some other processes, especially in autophagy, has been recently discovered. Plant exocyst is specific because most of its subunits have multiple paralogs. The most diversified subunit is EXO70, which is encoded by 23 paralogous genes in Arabidopsis thaliana. In this thesis, I dealt with subunit AtEXO70E2 (AT5G61010), which has been localized to double-membrane compartments considerably reminiscent of autophagosomes. These compartments were named EXPOs (for exocyst-positive organelles) and described as a component of unconventional protein secretion pathways. There are also hints that EXO70E2 could play a role in autophagic processes. However, details of this relationship remained unexplored. For my experiments, I used stably transformed lines of A. thaliana and transiently transformed leaves of Nicotiana benthamiana. I performed numerous colocalization experiments, applied various pharmacological treatments to the studied lines, and analyzed a mutant line in the EXO70E2 gene. According to my observations, protein EXO70E2 is expressed especially...
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Functions of RAB GTPases and SNARE proteins in post-Golgi trafficking pathways in response to abiotic stress in plants
Moulík, Michal ; Hála, Michal (advisor) ; Mašková, Petra (referee)
Plants as sessile organisms are strongly affected by abiotic and biotic stress factors. Thus, they have developed an array of morfological, biochemical and physiological adaptations to reduce the negative effects of these factors. The membrane trafficking, among others, plays very important role in adaptation to abiotic stress. In my bachelor thesis I have focused on two important protein families involved in this trafficking, namely on RAB GTPases and SNARE proteins. In the first part, the phenomenon of stress is characterized and the strategies how plants cope with the effect of stressors are described, especially the production of reactive oxygen species (ROS) and autophagy. Following chapter deals with an introduction to the membrane trafficking in plants. In the rest of the thesis, I characterize RAB GTPases and SNARE proteins and provide contemporary insight in the mechanism of their function. The aim of the key parts of these chapters is to summarize current knowledge of RAB GTPases' and SNARE proteins' functions in post-Golgi trafficking pathways during response to abiotic stressors or secondary oxidative stress. Key words: plants, abiotic stress, membrane trafficking, secretion, endocytosis, vacuole, RAB GTPases, SNARE proteins
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