The Amyloid Fibril-Forming β-Sheet Regions of Amyloid β and α-Synuclein Preferentially Interact with the Molecular Chaperone 14-3-3ζ.

Danielle M Williams,Joanna M Woodcock,John A Carver,Sarah Meehan,David C Thorn,Christopher M Dobson,Sophie E Jackson

doi:10.3390/molecules26206120

Abstract

14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid β (Aβ) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer’s and Parkinson’s diseases, respectively, a process that is intimately linked to the diseases’ progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aβ (Aβ40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aβ40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aβ40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt β-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased individuals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aβ40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.

Highlights

Protein aggregation is a characteristic of many diseases, the majority of which are age-related and neurological
We report on an NMR spectroscopic and biophysical analysis of the interaction of 14-3-3ζ, a major 14-3-3 isoform, with amyloid β (Aβ), and a similar interaction between 14-3-3ζ and A53T α-syn, a mutant of α-syn associated with familial PD that aggregates more rapidly than the wild type (WT) protein
More pronounced effects on the lag phase and extent of Aβ40 fibril formation Molecules 2021, 26, x FOR PEER REVwIEeWre observed at a 1.0:2.0 molar ratio, with complete inhibition of aggregation occurri4ngofa1t5 a 1.0:4.0 molar ratio of Aβ40:14-3-3ζ (Figure S1)

Summary

Introduction

Protein aggregation is a characteristic of many diseases, the majority of which are age-related and neurological. Common examples of protein aggregation diseases ( known as protein misfolding or protein conformational diseases) include Alzheimer’s (AD), Parkinson’s (PD), Huntington’s, and Creutzfeldt–Jakob [1,2]. The protein aggregates or deposits associated with these diseases contain a predominant peptide or protein that, in the majority of cases, adopts an amyloid fibrillar form. Amyloid fibrils are a highly stable, aggregated proteinaceous state with the polypeptide arranged mainly in a cross β-sheet conformation that results in an extended, overall fibrillar structure up to micrometers in length [1,2]. The conversion of a protein from its native, functional state to an amyloid fibril is a multi-step process that usually involves a nucleation-dependent mechanism that has various intermediate states, including the formation of prefibrillar oligomers that act as nuclei to sequester and convert natively structured proteins into the fibrillar form. The prefibrillar oligomers are proposed to be the entities that cause cell toxicity and, are intimately involved in the disease processes [1,2]

Methods

Results

Conclusion