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Exploring the role of post-translational modifications in regulating α-synuclein interactions by studying the effects of phosphorylation on nanobody binding.

Accepted version
Peer-reviewed

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Article

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Authors

El Turk, Farah 
De Genst, Erwin 
Guilliams, Tim 
Fauvet, Bruno 
Hejjaoui, Mirva 

Abstract

Intracellular deposits of α-synuclein in the form of Lewy bodies are major hallmarks of Parkinson's disease (PD) and a range of related neurodegenerative disorders. Post-translational modifications (PTMs) of α-synuclein are increasingly thought to be major modulators of its structure, function, degradation and toxicity. Among these PTMs, phosphorylation near the C-terminus at S129 has emerged as a dominant pathogenic modification as it is consistently observed to occur within the brain and cerebrospinal fluid (CSF) of post-mortem PD patients, and its level appears to correlate with disease progression. Phosphorylation at the neighboring tyrosine residue Y125 has also been shown to protect against α-synuclein toxicity in a Drosophila model of PD. In the present study we address the potential roles of C-terminal phosphorylation in modulating the interaction of α-synuclein with other protein partners, using a single domain antibody fragment (NbSyn87) that binds to the C-terminal region of α-synuclein with nanomolar affinity. The results reveal that phosphorylation at S129 has negligible effect on the binding affinity of NbSyn87 to α-synuclein while phosphorylation at Y125, only four residues away, decreases the binding affinity by a factor of 400. These findings show that, despite the fact that α-synuclein is intrinsically disordered in solution, selective phosphorylation can modulate significantly its interactions with other molecules and suggest how this particular form of modification could play a key role in regulating the normal and aberrant function of α-synuclein.

Description

Keywords

Parkinson's disease, isothermal titration calorimetry, nanobody), nuclear magnetic resonance, phosphorylation, protein misfolding, single-domain antibody (sdAb, surface plasmon resonance, α-synuclein, Autopsy, Binding Sites, Brain, Humans, Parkinson Disease, Phosphorylation, Protein Binding, Protein Processing, Post-Translational, Serine, Single-Domain Antibodies, Tyrosine, alpha-Synuclein

Journal Title

Protein Sci

Conference Name

Journal ISSN

0961-8368
1469-896X

Volume Title

27

Publisher

Wiley
Sponsorship
Medical Research Council (G1002272)