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Abstract :
[en] Several neurodegenerative disorders, called polyglutamine (polyQ) diseases, are associated with the aggregation into amyloid fibrils of proteins containing an expanded polyQ tract (>35-45 Q). Amyloid fibrils are proteinaceous aggregates with a helical organization. Such assemblies contain a large amount of b-sheet secondary structures.
How do non-polyQ regions of the proteins interfere with the propensity of polyQ tracts to trigger fibril formation?
The aim of this study is a better understanding of the role of polyQ and non-polyQ regions on the elongation of amyloid fibril. By performing fibril elongation in the presence of various chimeras and in different conditions, the aim is to unravel the effect of each parameter in general, and of the protein context in particular, on the elongation rate.
This requires AFM imaging in complement to QCM experiments. Imaging parameters have to be optimized for such sensitive and nanosized samples.
Accurate measurement of fibril elongation rate is performed by quartz crystal microbalance (QCM) and sensor surfaces are imaged by atomic force microscopy (AFM) before and after the elongation step.
BlaP is an ideal host protein, in order to better understand how non-polyQ regions interfere with the aggregation process of polyQ proteins. BlaP chimeras are a good model system because there is a Q-treshold for fibril formation ; the longer the polyQ, the faster the aggregation ; conformation and insertion site are critical.