The protein alpha-synuclein (aS) is implicated in the etiology of both familial and sporadic Parkinson's disease (PD). The interplay between the normal function of aS and its pathological aggregation is poorly understood, but membrane-bound forms of aS are thought to mediate its physiological function, while aggregated forms are thought to mediate the toxicity of the protein. Structurally, aS is highly malleable, adopting a highly disordered conformational ensemble when free in solution, highly helical structures when bound to phospholipids membranes and b-sheet rich conformations when aggregated into amyloid fibrils. Preventing the aggregation of aS into amyloid fibrils or potentially toxic oligomeric species is a promising strategy for the treatment of PD. The overarching goal of this research is to achieve a detailed understanding of how synuclein structural properties and transitions modulate synuclein function and toxicity and to identify specific conformational states of aS that could facilitate the design of synuclein-interacting reagents with potential therapeutic value. The current proposal is aimed at filling a newly emerged gaps in our understanding of aS structure that were created by a) the discovery of a new PD-linked aS mutation, E46K;b) the discovery that membrane-bound aS can adopt two different topologies, an extended helix and a broken helix, and the formulation of a hypothesis regarding how these two conformations may influence synuclein function;c) the discovery of new aS interaction partners thought to modulate synuclein function. To fill these gaps and to address emerging hypotheses we have developed the following specific aims: 1. To determine the effects of the most recently discovered PD-linked mutation, E46K, on structure in the free and membrane-bound forms of aS. 2. To elucidate at high resolution the extended-helix structure of membrane-bound aS. 3. To test the hypothesis that aS can mediate interactions between topologically distinct membranes of different compositions using its previously elucidated broken-helix structure. 4. To determine the effects of AARP16/19 binding on the structure of membrane-associated aS.
These aims are motivated by the opportunity to clarify how aS sequence variations influence the structure and aggregation of the protein, and by our belief that monomeric membrane-bound conformations of aS, which are more highly ordered, may be better suited to form specific interactions with potential therapeutics. This work will advance our understanding of aS structure, function, and aggregation and will provide a structural basis for the future design and identification of reagents that can stabilize monomeric aS and prevent its oligomerization and aggregation. Furthermore, the results obtained may have general implications for strategies to address protein aggregation in other age-related motor disorders and dementias.

Public Health Relevance

The protein alpha-synuclein is thought to play an important role in the etiology of Parkinson's disease. This proposal aims to improve our understanding of specific structural states of this protein, with the long-term goal of facilitating our ability to control the structural transitions of the protein in vivo. This ability is expected allow for the development of novel therapeutic strategies for the treatment of Parkinson's disease, the second most common neurodegenerative disorder, a goal with clear and significant implications for public health.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AG019391-13
Application #
8448160
Study Section
Biophysics of Neural Systems Study Section (BPNS)
Program Officer
Chen, Wen G
Project Start
2001-04-01
Project End
2015-03-31
Budget Start
2013-05-15
Budget End
2014-03-31
Support Year
13
Fiscal Year
2013
Total Cost
$314,692
Indirect Cost
$128,484
Name
Weill Medical College of Cornell University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Georgieva, Elka R; Xiao, Shifeng; Borbat, Peter P et al. (2014) Tau binds to lipid membrane surfaces via short amphipathic helices located in its microtubule-binding repeats. Biophys J 107:1441-52
Snead, David; Wragg, Rachel T; Dittman, Jeremy S et al. (2014) Membrane curvature sensing by the C-terminal domain of complexin. Nat Commun 5:4955
Fares, Mohamed-Bilal; Ait-Bouziad, Nadine; Dikiy, Igor et al. (2014) The novel Parkinson's disease linked mutation G51D attenuates in vitro aggregation and membrane binding of ?-synuclein, and enhances its secretion and nuclear localization in cells. Hum Mol Genet 23:4491-509
Mahul-Mellier, Anne-Laure; Fauvet, Bruno; Gysbers, Amanda et al. (2014) c-Abl phosphorylates ?-synuclein and regulates its degradation: implication for ?-synuclein clearance and contribution to the pathogenesis of Parkinson's disease. Hum Mol Genet 23:2858-79
Dikiy, Igor; Eliezer, David (2014) N-terminal acetylation stabilizes N-terminal helicity in lipid- and micelle-bound *-synuclein and increases its affinity for physiological membranes. J Biol Chem 289:3652-65
Wragg, Rachel T; Snead, David; Dong, Yongming et al. (2013) Synaptic vesicles position complexin to block spontaneous fusion. Neuron 77:323-34
Barre, Patrick; Eliezer, David (2013) Structural transitions in tau k18 on micelle binding suggest a hierarchy in the efficacy of individual microtubule-binding repeats in filament nucleation. Protein Sci 22:1037-48
Mesmin, Bruno; Pipalia, Nina H; Lund, Frederik W et al. (2011) STARD4 abundance regulates sterol transport and sensing. Mol Biol Cell 22:4004-15
Stratton, Margaret M; McClendon, Sebastian; Eliezer, David et al. (2011) Structural characterization of two alternate conformations in a calbindin D?k-based molecular switch. Biochemistry 50:5583-9