A Microplate-Based Approach to Map Interactions between TDP-43 and α-Synuclein

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Trans-active response DNA-binding protein (TDP-43) pathology is implicated in major neurodegenerative diseases like ALS and FTD.
• TDP-43 proteinopathies can co-occur with other proteinopathies, such as alpha synuclein aggregation in Lewy body disease.
• The potential for TDP-43 and alpha synuclein to co-aggregate and form comorbid pathologies requires further investigation.

Purpose of the Study:

• To investigate the hypothesis that alpha synuclein and TDP-43 co-aggregate, leading to combined synucleinopathy and TDP-43 proteinopathy.
• To identify specific interaction sites between TDP-43 and alpha synuclein.
• To characterize the binding affinity and interaction kinetics between these two proteins.

Main Methods:

• A solid-phase microplate-based immunoassay was employed to map TDP-43 antibody epitopes and detect TDP-43/alpha synuclein interactions.
• In silico sequence-based prediction was used to calculate binding affinity and dissociation constants.

Main Results:

• A specific region within the low complexity domain of TDP-43 (amino acids 311-314) was found to interact with full-length alpha synuclein.
• Full-length TDP-43 demonstrated binding to the non-amyloid beta component of alpha synuclein.
• In silico analysis yielded a binding affinity of -10.83 kcal/mol and a dissociation constant of 1.13 × 10^-8 for TDP-43 and alpha synuclein interaction.

Conclusions:

• The developed microplate-based method offers a convenient, economical, and rapid approach for identifying protein interaction sites and antibody epitopes.
• The findings provide evidence for direct interaction between TDP-43 and alpha synuclein, supporting their potential co-aggregation in neurodegenerative conditions.
• Understanding these molecular interactions is crucial for elucidating the pathogenesis of comorbid proteinopathies.