TY - JOUR

T1 - EGCG has Dual and Opposing Effects on the N-terminal Region of Self-associating α-synuclein Oligomers

AU - Grønnemose, Anne Louise

AU - Østerlund, Eva Christina

AU - Otzen, Daniel Erik

AU - Jørgensen, Thomas J.D.

N1 - Publisher Copyright: © 2022 The Author(s)

PY - 2022/12

Y1 - 2022/12

N2 - Oligomers of the protein α-synuclein (α-syn) are thought to be a major toxic species in Parkinson's disease, particularly through their ability to permeabilize cell membranes. The green tea polyphenol epigallocatechin gallate (EGCG) has been found to reduce this ability. We have analyzed α-syn oligomer dynamics and interconversion by H/D exchange monitored by mass spectrometry (HDX-MS). Our results show that the two oligomers OI and OII co-exist in equilibrium; OI is a multimer of OII and its dissociation can be followed by HDX-MS by virtue of the correlated exchange of the N-terminal region. Urea destabilizes the α-syn oligomers, dissociating OI to OII and monomers. Oligomers exposed to EGCG undergo Met oxidation. Intriguingly, EGCG induces an oxidation-dependent effect on the structure of the N-terminal region. For the non-oxidized N-terminal region, EGCG increases the stability of the folded structure as measured by a higher level of protection against H/D exchange. In contrast, protection is clearly abrogated in the Met oxidized N-terminal region. Having a non-oxidized and disordered N-terminal region is known to be essential for efficient membrane binding. Therefore, our results suggest that the combined effect of a structural stabilization of the non-oxidized N-terminal region and the presence of a disordered oxidized N-terminal region renders the oligomers less cytotoxic by decreasing the ability of the N-terminal region to bind to cell membranes and facilitate their permeabilization.

AB - Oligomers of the protein α-synuclein (α-syn) are thought to be a major toxic species in Parkinson's disease, particularly through their ability to permeabilize cell membranes. The green tea polyphenol epigallocatechin gallate (EGCG) has been found to reduce this ability. We have analyzed α-syn oligomer dynamics and interconversion by H/D exchange monitored by mass spectrometry (HDX-MS). Our results show that the two oligomers OI and OII co-exist in equilibrium; OI is a multimer of OII and its dissociation can be followed by HDX-MS by virtue of the correlated exchange of the N-terminal region. Urea destabilizes the α-syn oligomers, dissociating OI to OII and monomers. Oligomers exposed to EGCG undergo Met oxidation. Intriguingly, EGCG induces an oxidation-dependent effect on the structure of the N-terminal region. For the non-oxidized N-terminal region, EGCG increases the stability of the folded structure as measured by a higher level of protection against H/D exchange. In contrast, protection is clearly abrogated in the Met oxidized N-terminal region. Having a non-oxidized and disordered N-terminal region is known to be essential for efficient membrane binding. Therefore, our results suggest that the combined effect of a structural stabilization of the non-oxidized N-terminal region and the presence of a disordered oxidized N-terminal region renders the oligomers less cytotoxic by decreasing the ability of the N-terminal region to bind to cell membranes and facilitate their permeabilization.

KW - EGCG

KW - hydrogen/deuterium exchange

KW - mass spectrometry

KW - Met oxidation

KW - oligomer dynamics

KW - urea dissociation

KW - α-synuclein

UR - http://www.scopus.com/inward/record.url?scp=85140589348&partnerID=8YFLogxK

U2 - 10.1016/j.jmb.2022.167855

DO - 10.1016/j.jmb.2022.167855

M3 - Journal article

C2 - 36240861

AN - SCOPUS:85140589348

VL - 434

JO - Journal of Molecular Biology

JF - Journal of Molecular Biology

SN - 0022-2836

IS - 23

M1 - 167855

ER -