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Molecular biological, structural and functional analysis concerning the mechanism of membrane fusion in Paramecium cells

Molecular biological, structural and functional analysis concerning the mechanism of membrane fusion in Paramecium cells

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WASSMER, Thomas, 2005. Molecular biological, structural and functional analysis concerning the mechanism of membrane fusion in Paramecium cells [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Wassmer2005Molec-6549, title={Molecular biological, structural and functional analysis concerning the mechanism of membrane fusion in Paramecium cells}, year={2005}, author={Wassmer, Thomas}, address={Konstanz}, school={Universität Konstanz} }

Molecular biological, structural and functional analysis concerning the mechanism of membrane fusion in Paramecium cells application/pdf Wassmer, Thomas Molekularbiologische, strukturelle und funktionelle Analysen zum Mechanismus der Membranfusion in Paramecium-Zellen eng Wassmer, Thomas 2011-03-24T17:27:20Z 2011-03-24T17:27:20Z 2005 At the moment exist two models of the fusion of biological membranes in the scientifique literature. i.) The basis of the SNARE-hypothesis (Soluble NSF Attachment Protein Receceptors) is that membrane-anchored protein complexes between opposing membranes can drive mixing between lipids of the different membranes, induce hemi-fusion intermediates and lead to membrane fusion. Central in this hypothesis are the SNARE-proteins syntaxin, synaptobrevin and SNAP-25. ii.) In the pore-hypothesis a proteinacious pore that spans two opposing membranes is postulated. Lipids are thought to invade the pore, leading to a lipid filled protein channel connecting the two membranes. Dissociation and lateral diffusion of the pore subunits is assumed to complete the fusion reaction. In the pore hypothesis the transmembraneous part (V0) of the vacuolar ATPase (V-ATPase) is currently discussed as fusogene.<br />A goal of this thesis was to identify in the genome project of the ciliate Paramecium tetraurelia all the genes encoding SNAREs and the V0-sector of the V-ATPase and to analyse some of the genes in more detail. The first goal was to test whether it was possible to find hints about the participation of V0 in the exocytosis of dense core secretory granules (trichocysts) in Paramecium. The second goal was to identify SNARE-proteins that may be involved in the exocytosis of trichocysts.<br />During this thesis in collaboration with co-workers of the Plattner laboratory at the University of Konstanz, Germany, and the Cohen lab at the CNRS in Gif-sur-Yvette, France, almost all genes of the V-ATPase could be identified. Six c-subunit genes of V0 and two F-subunit genes of V1 were investigated in more detail by using green fluorescent protein (GFP) localization techniques and a functional approach by using RNA interference (RNAi). The results of the study are published in Wassmer et al., (2005, Chapter 2). Further works on the a-subunit of V0 showed that this subunit is encoded by 17 genes whose products are targeted to widely different compartments (Wassmer et al., 2005, submitted, Chapter 3). On established membrane fusion sites no V0-subunits could be detected, so from the two manuscripts it can be concluded that a participation of V0 in membrane fusion in Paramecium is highly unlikely.<br />During this thesis 15 synaptobrevin- and 26 syntaxin-encoding genes could be indentified. In phylogenetic studies, localization using GFP/isoform-specific antibodies and functional tests using RNAi many SNARE genes could be attributed to different trafficking pathways in the Paramecium cell (Schilde et al., 2005, submitted, Chapter 4). Within the syntaxins, one could be identified whose gene product is localized in the plasma membrane. This result will allow a closer characterization of the role of syntaxin in regulated exocytosis in the future (Kissmehl et al., 20005, in preparation, Chapter 5). deposit-license

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

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