| Amyloid aggregates are hallmarks of neurodegenerative diseases such as Alzheimer?s, Parkinson?s, and Huntington?s disease, and of the prion diseases. Early stage aggregates of the alpha-synuclein protein are hypothesized to be the determinants of toxicity and cell-death in Parkinson?s disease. Yet the molecular architecture and structure of these aggregates and the mechanisms by which they cause cell damage remains a mystery. There are indications that the oligomers may disrupt or permeabilize cellular membranes by forming pores, analogous to the bacterial pore-forming toxins, leading to disruption of calcium regulation and cell-death. On longer length-scales, some amyloid fibers are known to organize into mesoscopic structures. Spherulites containing amyloid-beta protein are characteristic of Alzheimer's disease while the brain of Parkinson patients contains Lewy bodies; aggregates of alpha-synuclein. The assembly of protein polymers into mesoscopic aggregates such as bundles, spherulites, protein particulates or lamellar phases has also been observed in vitro. However, in spite of the myriad of mesoscopic amyloid aggregates and their appearance in disease, little is known about the protein structural motifs and physical forces underlying this mesoscopic polymer aggregation. This proposal intends to study essential biophysical aspects of the aggregation processes of the intrinsically disordered protein alpha-synuclein across length scales and the relevance of early aggregate species to disease. We ask the following specific questions: " What kind of early aggregate species are formed and what are their structures and physical properties? " How do these aggregates partition into model lipids and cell membrane mimics? " What are the physical and chemical forces modulating the supramolecular assembly of mesoscopic alpha-synuclein aggregates? Using a variety of biochemical and biophysical methods, including high-resolution optical and scanning probe microscopy, and single-molecule spectroscopy we aim to get detailed insights into the biophysics and chemical biology of alpha-synuclein aggregation. We will quantitatively image and characterize defined aggregate species, and explore the interaction of these aggregates with lipid bilayers. The fundamental biophysical understanding will shed light on the crucial molecular biophysical question of medically-relevant protein self-assembly and aggregation. This research will link molecular biophysics, nanobiotechnology, and chemical biology to address an important biomedical problem. |
