Dataset Information

First direct observation of elongated conformational states in alpha-synuclein upon liquid-liquid phase separation

ABSTRACT: α-Synuclein (α-syn) is an intrinsically disordered protein (IDP) that undergoes liquid-liquid phase separation (LLPS), fibrillation, and forms insoluble intracellular Lewy’s bodies in neurons, which are the hallmark of Parkinson’s Disease (PD). Neurotoxicity precedes the formation of aggregates and is probably related to LLPS of α-syn in the cell. The molecular mechanisms underlying the early stages of LLPS are still elusive. To obtain structural insights into α-syn upon LLPS, we take advantage of cross-linking/mass spectrometry (XL-MS) and introduced an innovative new approach, termed COMPASS (COMPetitive PAiring StatisticS). COMPASS unravels transient interactions between α-syn molecules in liquid droplets to derive structural information of α-syn upon LLPS. In this work, we show that the conformational ensemble of α-syn shifts towards more elongated conformational states upon LLPS. We obtain insights into the critical initial stages of PD and establish a novel mass spectrometry-based approach that will aid to solve open questions in LLPS structural biology.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Daniele Ubbiali

LAB HEAD: Andrea Sinz

PROVIDER: PXD033205 | Pride | 2024-03-18

REPOSITORIES: Pride

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Publications

Direct Observation of "Elongated" Conformational States in α-Synuclein upon Liquid-Liquid Phase Separation.

Ubbiali Daniele D Fratini Marta M Piersimoni Lolita L Ihling Christian H CH Kipping Marc M Heilmann Ingo I Iacobucci Claudio C Sinz Andrea A

Angewandte Chemie (International ed. in English) 20221017 46

α-Synuclein (α-syn) is an intrinsically disordered protein (IDP) that undergoes liquid-liquid phase separation (LLPS), fibrillation, and forms insoluble intracellular Lewy bodies in neurons, which are the hallmark of Parkinson's Disease (PD). Neurotoxicity precedes the formation of aggregates and might be related to α-syn LLPS. The molecular mechanisms underlying the early stages of LLPS are still elusive. To obtain structural insights into α-syn upon LLPS, we take advantage of cross-linking/mas ...[more]

PMID: 36115020

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Project description:Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder caused by dopaminergic neuronal deaths. For a proper treatment of PD, biomarkers that would enable us to monitor disease progression or responses to a disease-modifying agent, or that can be used as a presymptomatic marker are critical. In addition, a biomarker that could be used to distinguish between the various diseases that manifest with PD-like symptoms would greatly enhance patient care and management of future clinical trials. Previous research indicates that c-Abl is overactive in PD patients resulting in an increased phosphorylation of the tyrosine 39 residue of alpha-synuclein (a-syn) (pY39 a-syn) and eventually dopaminergic neuronal death via a-syn aggregation. For this reason, monitoring pY39 a-syn will enable us to diagnose presymptomatic PD, monitoring disease progression and monitoring the response disease-modifying agents. We hypothesized that this increased phosphorylation on Y39 of a-syn (pY39 a-syn) will be reflected in the cerebrospinal fluid (CSF) of PD patients and monitoring pY39 a-syn level in CSF will enable us to monitor pY39 a-syn level in the brain. Mass spectrometry has been widely used for the detection of phosphorylated peptides using parallel reaction monitoring (PRM) and we utilized the PRM mass spectrometry for the detection of pY39 a-syn. However, pY39 a-syn was not detected even after immunoprecipitation of a-syn, phosphopeptide enrichment or phosphotyrosine peptide enrichment from a practical volume. For this reason, we have developed a two-step enrichment method in which pY39 a-syn was first enriched with an anti-phosphotyrosine antibody followed by a further enrichment of phosphopeptides with titanium oxide (TiO2) beads to remove non-phosphopeptides. Accurate quantification was obtained by including a synthetic pY39 a-syn peptide labeled with heavy lysine that was added before an enzyme digestion. To detect pY39 α-syn peptide in CSF lower than 10 femtomolar concentration, experimental parameters were optimized. Comparison of pY39 a-syn to total a-syn in CSF from PD patients and controls reveals that pY39 a-syn levels are significantly elevated in the CSF of PD patient versus controls. This optimized two-step enrichment PRM detection method may be of value as a biomarker to monitor c-Abl activation in PD patients for future diagnostic studies as well as a pharmacodynamic marker for c-Abl therapeutic trials in PD. Furthermore, this developed method can be applicable to quantifying other phosphotyrosine peptides with low abundance in biological samples.

Dataset Information

First direct observation of elongated conformational states in alpha-synuclein upon liquid-liquid phase separation

Publications

Direct Observation of "Elongated" Conformational States in α-Synuclein upon Liquid-Liquid Phase Separation.

Similar Datasets

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