Mapping the binding site topology of amyloid protein aggregates using multivalent ligands.

Elena Sanna,Klara Kulenkampff,Franklin I Aigbirhio,Steven G Fagan,Christopher A Hunter,David Klenerman,Margarida Rodrigues,Maria Grazia Spillantini,Timothy S Chisholm

doi:10.1039/d1sc01263k

Elena Sanna, Klara Kulenkampff + Show 7 more

Open Access

https://doi.org/10.1039/d1sc01263k

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Abstract

A key process in the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases is the aggregation of proteins to produce fibrillary aggregates with a cross β-sheet structure, amyloid. The development of reagents that can bind these aggregates with high affinity and selectivity has potential for early disease diagnosis. By linking two benzothiazole aniline (BTA) head groups with different length polyethylene glycol (PEG) spacers, fluorescent probes that bind amyloid fibrils with low nanomolar affinity have been obtained. Dissociation constants measured for interaction with Aβ, α-synuclein and tau fibrils show that the length of the linker determines binding affinity and selectivity. These compounds were successfully used to image α-synuclein aggregates in vitro and in the post-mortem brain tissue of patients with Parkinson's disease. The results demonstrate that multivalent ligands offer a powerful approach to obtain high affinity, selective reagents to bind the fibrillary aggregates that form in neurodegenerative disease.

Highlights

Neurodegenerative disorders like Alzheimer's and Parkinson's diseases are a growing medical problem in modern society.[1]
benzothiazole aniline (BTA) dimers were synthesised with oligoethylene glycol linkers between 3 and 21 ethylene glycol units in length
The titration data must be analysed allowing for the emission of both the free and bound BTA dimer

Summary

Introduction

Neurodegenerative disorders like Alzheimer's and Parkinson's diseases are a growing medical problem in modern society.[1]. Values of effective molarity generally fall in the range 10–100 mM, even for long exible linkers, so provided a ligand head group with a Kd signi cantly lower than 10 mM is used, signi cant enhancements in binding affinity can be expected.[7,8] Identi cation of the optimal linker length for different amyloid proteins (Ab, a-synuclein or tau) will provide insights into the differences in the binding site topologies of the aggregates, providing new strategies for improving selectivity.

Results

Conclusion