Changes in secondary structure of α-synuclein during oligomerization induced by reactive aldehydes.
2015 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 464, no 1, 336-341 p.Article in journal (Refereed) Published
The oxidative stress-related reactive aldehydes 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE) have been shown to promote formation of α-synuclein oligomers in vitro. However, the changes in secondary structure of α-synuclein and the kinetics of the oligomerization process are not known and were the focus of this study. Size exclusion chromatography showed that after 1 h of incubation, HNE induced the formation of an oligomeric α-synuclein peak with a molecular weight of about ∼2000 kDa, which coincided with a decreasing ∼50 kDa monomeric peak. With prolonged incubation (up to 24 h) the oligomeric peak became the dominating molecular species. In contrast, in the presence of ONE, a ∼2000 oligomeric peak was exclusively observed after 15 min of incubation and this peak remained constant with prolonged incubation. Western blot analysis of HNE-induced α-synuclein oligomers showed the presence of monomers (15 kDa), SDS-resistant low molecular (30-160 kDa) and high molecular weight oligomers (≥260 kDa), indicating that the oligomers consisted of both covalent and non-covalent protein. In contrast, ONE-induced α-synuclein oligomers only migrated as covalent cross-linked high molecular-weight material (≥300 kDa). Both circular dichroism (CD) and Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy showed that the formation of HNE- and ONE-induced oligomers coincided with a spectral change from random coil to β-sheet. However, ONE-induced α-synuclein oligomers exhibited a slightly higher degree of β-sheet. Taken together, our results indicate that both HNE and ONE induce a change from random coil to β-sheet structure that coincides with the formation of α-synuclein oligomers. Albeit through different kinetic pathways depending on the degree of cross-linking.
Place, publisher, year, edition, pages
2015. Vol. 464, no 1, 336-341 p.
Biophysics Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy) Engineering and Technology
IdentifiersURN: urn:nbn:se:uu:diva-257598DOI: 10.1016/j.bbrc.2015.06.154ISI: 000359173200053PubMedID: 26129771OAI: oai:DiVA.org:uu-257598DiVA: diva2:840079
FunderMarianne and Marcus Wallenberg Foundation