From monomer to fibrils: the alpha-synuclein journey lit up by fluorescence.

CELEJ MS, THIRUNAVUKKUARASU S, ROBERTI MJ, KLEMENT R, PELAH A, CAARLS W, DEMCHENKO A, JARES-ERIJMAN E, JOVIN TM

Goettingen

Otro; Doktorandenseminar; 2008

Instituto Max Planck de Biofisico-Química

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> Parkinson’s disease (PD) and several other related neurodegenerative disorders are featured by the loss of dopaminergic neurons in the midbrain, presumably as a consequence of mitochondrial and ubiquitin-proteasomal dysfunction. A pathological hallmark of these disorders is the presence of intracytoplasmatic inclusions (Lewy bodies), of which the main fibrillar constituent is the 140-aa protein a-synuclein (AS). AS is located presynaptically and functions in vesicle release and trafficking. Three missense point mutations (A53T, A30P and E46K) in the AS gene leads to early onset PD. Cytotoxicity is currently attributed to the action of intermediate (oligomeric) species rather than the classical end-state amyloid fibrils. A major effort in our lab is directed at devising new fluorescence-based methods for detecting and characterizing oligomeric species of wildtype (WT) and the familial mutants of AS. We have employed both external as well as covalently attached environment-sensitive probes, which also provide information related to structural aspects not revealed by classical amyloid dyes. For example, novel dual-emission color probes report differences in the supramolecular organization of amyloid fibrils formed by WT and mutant AS, which can be interpreted in terms of distinctive polarity and hydration of the binding sites. Further studies along these lines may help to elucidate the phenomenon of polymorphism and strain-specific propagation in amyloidosis, and to develop therapeutic agents.Essential supporting tools in this endeavor have been structural modeling by molecular dynamics, AFM analysis of aggregated species, and, most recently, two-color imaging by PALM superresolution microscopy (a collaboration with the Nanobiophotonic Department). The latter technique permits the visualization of monomer addition and/or exchange with fibrillar forms of AS.  Our work on AS has also involved intensive and very fruitful collaborations with the various solution and solid state NMR groups of the institute (M. Baldus, C. Griesinger, M. Zweckstetter) and the newly formed EPR Spectroscopy group (M. Bennati). Support has been from the MPG and the CMPB. MSC is grateful to AvH Foundation for her postdoctoral fellowship.