Amyloidogenic mutation promotes fibril formation of the N-terminal apolipoprotein A-I on lipid membranes

Chiharu Mizuguchi, Fuka Ogata, Shiho Mikawa, Kohei Tsuji, Teruhiko Baba, Akira Shigenaga, Toshinori Shimanouchi, Keiichiro Okuhira, Akira Otaka, Hiroyuki Saito

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The N-terminal amino acid 1-83 fragment of apolipoprotein A-I (apoA-I) has a strong propensity to form amyloid fibrils at physiological neutral pH. Because apoA-I has an ability to bind to lipid membranes, we examined the effects of the lipid environment on fibril-forming properties of the N-terminal fragment of apoA-I variants. Thioflavin T fluorescence assay as well as fluorescence and transmission microscopies revealed that upon lipid binding, fibril formation by apoA-I 1-83 is strongly inhibited, whereas the G26R mutant still retains the ability to form fibrils. Such distinct effects of lipid binding on fibril formation were also observed for the amyloidogenic prone region-containing peptides, apoA-I 8-33 and 8-33/G26R. This amyloidogenic region shifts from random coil to α-helical structure upon lipid binding. The G26R mutation appears to prevent this helix transition because lower helical propensity and more solvent-exposed conformation of the G26R variant upon lipid binding were observed in the apoA-I 1-83 fragment and 8-33 peptide. With a partially α-helical conformation induced by the presence of 2,2,2-trifluoroethanol, fibril formation by apoA-I 1- 83 was strongly inhibited, whereas the G26R variant can form amyloid fibrils. These findings suggest a new possible pathway for amyloid fibril formation by the N-terminal fragment of apoA-I variants: the amyloidogenic mutations partially destabilize the α-helical structure formed upon association with lipid membranes, resulting in physiologically relevant conformations that allow fibril formation.

Original languageEnglish
Pages (from-to)20947-20959
Number of pages13
JournalJournal of Biological Chemistry
Volume290
Issue number34
DOIs
Publication statusPublished - Aug 21 2015

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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