Kinetics of the Interactions between Copper and Amyloid-β with FAD Mutations and Phosphorylation at the N terminus.

Paul Girvan,Toru Miyake,Liming Ying,Thomas Branch,Xiangyu Teng

doi:10.1002/cbic.201600255

Abstract

Mutations and post‐translational modifications of amyloid‐β (Aβ) peptide in its N terminus have been shown to increase fibril formation, yet the molecular mechanism is not clear. Here we investigated the kinetics of the interactions of copper with two Aβ peptides containing Familial Alzheimer's disease (FAD) mutations (English (H6R) and Tottori (D7N)), as well as with Aβ peptide phosphorylated at serine 8 (pS8). All three peptides bind to copper with a similar rate as the wild‐type (wt). The dissociation rates follow the order pS8>H6R>wt>D7N; the interconversion between the two coordinating species occurs 50 % faster for H6R and pS8, whereas D7N had only a negligible effect. Interestingly, the rate of ternary complex (copper‐bridged heterodimer) formation for the modified peptides was significantly faster than that for wt, thus leading us to propose that FAD and sporadic AD might share a kinetic origin for the enhanced oligomerisation of Aβ.

Highlights

Alzheimer’s disease (AD) is the most common form of dementia, currently affecting 46 million people worldwide.[1]
In order to study the effects of H6R and D7N mutations and Ser8 phosphorylation on the binding kinetics of copper to Ab we employed stopped-flow techniques, by using the quenching properties of copper on a bright fluorophore covalently attached to Ab.[33]
The kinetics of the interaction between copper and two Ab mutants linked to Familial Alzheimer’s disease (FAD) and one phosphorylated at Ser8 has been determined

Summary

Full Papers

Paul Girvan,[b, c] Toru Miyake,[a, d] Xiangyu Teng,[b, c] Thomas Branch,[b, c] and Liming Ying*[a, b]. Mutations and post-translational modifications of amyloidb (Ab) peptide in its N terminus have been shown to increase fibril formation, yet the molecular mechanism is not clear. We investigated the kinetics of the interactions of copper with two Ab peptides containing Familial Alzheimer’s disease (FAD) mutations (English (H6R) and Tottori (D7N)), as well as with Ab peptide phosphorylated at serine 8 (pS8). The dissociation rates follow the order pS8 > H6R > wt > D7N; the interconversion between the two coordinating species occurs 50 % faster for H6R and pS8, whereas D7N had only a negligible effect. The rate of ternary complex (copperbridged heterodimer) formation for the modified peptides was significantly faster than that for wt, leading us to propose that FAD and sporadic AD might share a kinetic origin for the enhanced oligomerisation of Ab

Introduction

Results and Discussion

Conclusions

Experimental Section