Dataset Information

Site-Specific Fluorescence Polarization for Studying the Disaggregation of ?-Synuclein Fibrils by Small Molecules.

ABSTRACT: Fibrillar aggregates of the protein ?-synuclein (?S) are one of the hallmarks of Parkinson's disease. Here, we show that measuring the fluorescence polarization (FP) of labels at several sites on ?S allows one to monitor changes in the local dynamics of the protein after binding to micelles or vesicles, and during fibril formation. Most significantly, these site-specific FP measurements provide insight into structural remodeling of ?S fibrils by small molecules and have the potential for use in moderate-throughput screens to identify small molecules that could be used to treat Parkinson's disease.

SUBMITTER: Haney CM

PROVIDER: S-EPMC5520965 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Publications

Site-Specific Fluorescence Polarization for Studying the Disaggregation of α-Synuclein Fibrils by Small Molecules.

Haney Conor M CM Cleveland Christina L CL Wissner Rebecca F RF Owei Lily L Robustelli Jaclyn J Daniels Malcolm J MJ Canyurt Merve M Rodriguez Priscilla P Ischiropoulos Harry H Baumgart Tobias T Petersson E James EJ

Biochemistry 20161111 5

Fibrillar aggregates of the protein α-synuclein (αS) are one of the hallmarks of Parkinson's disease. Here, we show that measuring the fluorescence polarization (FP) of labels at several sites on αS allows one to monitor changes in the local dynamics of the protein after binding to micelles or vesicles, and during fibril formation. Most significantly, these site-specific FP measurements provide insight into structural remodeling of αS fibrils by small molecules and have the potential for use in ...[more]

PMID: 28045494

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Project description:Amyloidlike fibrils are found in many fatal diseases, including Alzheimer's disease, type II diabetes mellitus, transmissible spongiform encephalopathies, and prion diseases. These diseases are linked to proteins that have partially unfolded, misfolded, and aggregated into amyloidlike fibrils. The kinetics of amyloidlike fibrils aggregation is still hotly debated and remains an important open question. We have utilized the GNNQQNY crystal structure and high-temperature molecular dynamics simulation in explicit solvent to study the disaggregation mechanism of the GNNQQNY fibrils and to infer its likely aggregation pathways. A hexamer model and a 12-mer model both with two parallel beta-sheets separated by a dry side-chain interface were adopted in our computational analysis. A cumulative time of 1 micros was simulated for the hexamer model at five different temperatures (298 K, 348 K, 398 K, 448 K, and 498 K), and a cumulative time of 2.1 micros was simulated for the 12-mer model at four temperatures (298 K, 398 K, 448 K, and 498 K). Our disaggregation landscape and kinetics analyses indicate that tetramers probably act as the transition state in both the hexamer and the 12-mer simulations. In addition, the 12-mer simulations show that the initial aggregation nucleus is with eight peptides. Furthermore, the landscape is rather flat from 8-mers to 12-mers, indicating the absence of major barriers once the initial aggregation nucleus forms. Thus, the likely aggregation pathway is from monomers to the initial nucleus of 8-mers with tetramers as the transition state. Transition state structure analysis shows that the two dominant transition state conformations are tetramers in the 3-1 and 2-2 arrangements. The predominant nucleus conformations are in peptide arrangements maximizing dry side-chain contacts. Landscape and kinetics analyses also indicate that the parallel beta-sheets form earlier than the dry side-chain contacts during aggregation. These results provide further insights in understanding the early fibrils aggregation.

Dataset Information

Site-Specific Fluorescence Polarization for Studying the Disaggregation of ?-Synuclein Fibrils by Small Molecules.

Publications

Site-Specific Fluorescence Polarization for Studying the Disaggregation of α-Synuclein Fibrils by Small Molecules.

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