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

ABSTRACT: Intracellular deposits of ?-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 ?-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 ?-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 ?-synuclein with other protein partners, using a single domain antibody fragment (NbSyn87) that binds to the C-terminal region of ?-synuclein with nanomolar affinity. The results reveal that phosphorylation at S129 has negligible effect on the binding affinity of NbSyn87 to ?-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 ?-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 ?-synuclein.

SUBMITTER: El Turk F 

PROVIDER: S-EPMC6032363 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature