Biochemical identification of a linear cholesterol-binding domain within Alzheimer's β amyloid peptide

ACS Chem Neurosci. 2013 Mar 20;4(3):509-17. doi: 10.1021/cn300203a. Epub 2012 Dec 27.

Abstract

Alzheimer's β-amyloid (Aβ) peptides can self-organize into amyloid pores that may induce acute neurotoxic effects in brain cells. Membrane cholesterol, which regulates Aβ production and oligomerization, plays a key role in this process. Although several data suggested that cholesterol could bind to Aβ peptides, the molecular mechanisms underlying cholesterol/Aβ interactions are mostly unknown. On the basis of docking studies, we identified the linear fragment 22-35 of Aβ as a potential cholesterol-binding domain. This domain consists of an atypical concatenation of polar/apolar amino acid residues that was not previously found in cholesterol-binding motifs. Using the Langmuir film balance technique, we showed that synthetic peptides Aβ17-40 and Aβ22-35, but not Aβ1-16, could efficiently penetrate into cholesterol monolayers. The interaction between Aβ22-35 and cholesterol was fully saturable and lipid-specific. Single-point mutations of Val-24 and Lys-28 in Aβ22-35 prevented cholesterol binding, whereas mutations at residues 29, 33, and 34 had little to no effect. These data were consistent with the in silico identification of Val-24 and Lys-28 as critical residues for cholesterol binding. We conclude that the linear fragment 22-35 of Aβ is a functional cholesterol-binding domain that could promote the insertion of β-amyloid peptides or amyloid pore formation in cholesterol-rich membrane domains.

MeSH terms

  • Amino Acid Sequence
  • Amyloid beta-Peptides / chemistry
  • Amyloid beta-Peptides / genetics
  • Amyloid beta-Peptides / metabolism*
  • Binding Sites / physiology
  • Biochemical Phenomena
  • Cholesterol / chemistry
  • Cholesterol / genetics*
  • Cholesterol / metabolism*
  • Humans
  • Molecular Sequence Data
  • Protein Structure, Secondary
  • Protein Structure, Tertiary / physiology

Substances

  • Amyloid beta-Peptides
  • Cholesterol