Amyloid formation of fish β-parvalbumin involves primary nucleation triggered by disulfide-bridged protein dimers
Artikel i vetenskaplig tidskrift, 2020

Amyloid formation involves the conversion of soluble protein species to an aggregated state. Amyloid fibrils of β-parvalbumin, a protein abundant in fish, act as an allergen but also inhibit the in vitro assembly of the Parkinson protein α-synuclein. However, the intrinsic aggregation mechanism of β-parvalbumin has not yet been elucidated. We performed biophysical experiments in combination with mathematical modeling of aggregation kinetics and discovered that the aggregation of β-parvalbumin is initiated by the formation of dimers stabilized by disulfide bonds and then proceeds via primary nucleation and fibril elongation processes. Dimer formation is accelerated by H2O2 and hindered by reducing agents, resulting in faster and slower aggregation rates, respectively. Purified β-parvalbumin dimers readily assemble into amyloid fibrils with similar morphology as those formed when starting from monomer solutions. Furthermore, addition of preformed dimers accelerates the aggregation reaction of monomers. Aggregation of purified β-parvalbumin dimers follows the same kinetic mechanism as that of monomers, implying that the rate-limiting primary nucleus is larger than a dimer and/or involves structural conversion. Our findings demonstrate a folded protein system in which spontaneously formed intermolecular disulfide bonds initiate amyloid fibril formation by recruitment of monomers. This dimer-induced aggregation mechanism may be of relevance for human amyloid diseases in which oxidative stress is often an associated hallmark.

dimer formation

amyloid fibrils

disulfide bond

dimer-induced aggregation

kinetic analysis

Författare

Tony Werner

Chalmers, Biologi och bioteknik, Kemisk biologi

David Bernson

Chalmers, Biologi och bioteknik, Kemisk biologi

Elin K. Esbjorner

Sandra Rocha

Chalmers, Biologi och bioteknik, Kemisk biologi

Pernilla Wittung Stafshede

Chalmers, Biologi och bioteknik, Kemisk biologi

Proceedings of the National Academy of Sciences of the United States of America

0027-8424 (ISSN) 1091-6490 (eISSN)

Vol. 117 45 27997-28004 0027-842

Ämneskategorier

Biokemi och molekylärbiologi

Biofysik

DOI

10.1073/pnas.2015503117

Mer information

Skapat

2020-11-18