guest ::
| Home > Publications database > Structural and biophysical characterization of $\alpha$-synuclein and itsinteraction with lipid membranes |
| Home > Publications database > Structural and biophysical characterization of $\alpha$-synuclein and itsinteraction with lipid membranes |
| Dissertation / PhD Thesis | PUBDB-2015-00716 |
2014
Abstract: Parkinson's disease (PD) is a pervasive neurodegenerative disorder affecting millions of lives worldwide. There is currently no cure for PD and the pharmacological treatment is hence only symptomatic. Despite immense scientific efforts, there is still a lack of basic understanding of the pathogenesis of PD. Such understanding might be the key to optimized drug discovery strategies. Due to the outspoken similarities between PD and a number of other neurodegenerative and amyloid diseases, an enhanced understanding of PD is potentially also of general interest.PD is hallmarked by the presence of lipid-rich protein inclusions in the brain called Lewy Bodies (LB). LB are characterized by a high content of the $\alpha$-synuclein ($\alpha$SN) protein. A number of familiar point mutations within $\alpha$SN have been shown to cause early-onset genetic PD. The native structure of αSN is generally believed to be intrinsically disordered. However, within LB $\alpha$SN is found as elongated aggregates (amyloid fibrils) characterized by cross-$\beta$ structure. The fibrillated $\alpha$SN found in LB is believed to be an inert reservoir. The cytotoxic effect of $\alpha$SN is allegedly associated with the occurrence of transient oligomer structures that form prior to the formation of amyloid fibrils. Several studies have sought to elucidate on the molecular mechanism of $\alpha$SN interaction with lipid membranes in relation to the apparent cytotoxicity of oligomeric $\alpha$SN.This thesis presents experimental work addressing the structure of $\alpha$SN, aspects of $\alpha$SN-membrane interaction and process behind $\alpha$SN mutant fibrillation. The primary experimental methods are small-angle X-ray scattering (SAXS) and fluorescence spectroscopy with emphasis on the environmental sensitive dye Laurdan.During purification of $\alpha$SN we observed an unexpected chromatographic feature. This feature was revealed to be a consequence of the formation of partly compacted covalent αSN dimers as shown by e.g. SAXS and mass spectroscopy. Two projects were performed on the interactions of $\alpha$SN and lipid membranes. Here we showed that $\alpha$SN is able to dehydrate anionic membranes and to induce lysis of liposomes associated with the formation of $\alpha$-helical rich $\alpha$SN-lipid co-aggregates. Additionally we showed that cholesterol could modulate the interaction between $\alpha$SN oligomers and otherwise inert neutral lipid membranes. Finally a SAXS based study was conducted on the fibrillation of $\alpha$SN E46K mutant proving that the fibrillation of E46K is significantly different from that of wild-type $\alpha$SN under the applied conditions.
Keyword(s): Dissertation
|
The record appears in these collections: |