Probing the mechanism of inhibition of amyloid-β(1-42)-induced neurotoxicity by the chaperonin GroEL

Proc Natl Acad Sci U S A. 2018 Dec 18;115(51):E11924-E11932. doi: 10.1073/pnas.1817477115. Epub 2018 Dec 3.


The human chaperonin Hsp60 is thought to play a role in the progression of Alzheimer's disease by mitigating against intracellular β-amyloid stress. Here, we show that the bacterial homolog GroEL (51% sequence identity) reduces the neurotoxic effects of amyloid-β(1-42) (Aβ42) on human neural stem cell-derived neuronal cultures. To understand the mechanism of GroEL-mediated abrogation of neurotoxicity, we studied the interaction of Aβ42 with GroEL using a variety of biophysical techniques. Aβ42 binds to GroEL as a monomer with a lifetime of ∼1 ms, as determined from global analysis of multiple relaxation-based NMR experiments. Dynamic light scattering demonstrates that GroEL dissolves small amounts of high-molecular-weight polydisperse aggregates present in fresh soluble Aβ42 preparations. The residue-specific transverse relaxation rate profile for GroEL-bound Aβ42 reveals the presence of three anchor-binding regions (residues 16-21, 31-34, and 40-41) located within the hydrophobic GroEL-consensus binding sequences. Single-molecule FRET analysis of Aβ42 binding to GroEL results in no significant change in the FRET efficiency of a doubly labeled Aβ42 construct, indicating that Aβ42 samples a random coil ensemble when bound to GroEL. Finally, GroEL substantially slows down the disappearance of NMR visible Aβ42 species and the appearance of Aβ42 protofibrils and fibrils as monitored by electron and atomic force microscopies. The latter observations correlate with the effect of GroEL on the time course of Aβ42-induced neurotoxicity. These data provide a physical basis for understanding how Hsp60 may serve to slow down the progression of Alzheimer's disease.

Keywords: NMR spectroscopy; amyloid β–chaperonin interactions; electron microscopy; fluorescence resonance energy transfer; neurotoxicity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Alzheimer Disease / metabolism
  • Amyloid beta-Peptides / drug effects*
  • Amyloid beta-Peptides / genetics
  • Chaperonin 60 / antagonists & inhibitors*
  • Chaperonin 60 / metabolism*
  • Chaperonin 60 / therapeutic use
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • GTP-Binding Protein beta Subunits / metabolism
  • Humans
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Microscopy, Atomic Force
  • Microscopy, Electron
  • Models, Molecular
  • Neural Stem Cells / drug effects
  • Neurotoxicity Syndromes / drug therapy
  • Neurotoxicity Syndromes / metabolism*
  • Peptide Fragments / drug effects*
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Protein Aggregation, Pathological / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Domains
  • Staining and Labeling


  • Amyloid beta-Peptides
  • Chaperonin 60
  • GTP-Binding Protein beta Subunits
  • Peptide Fragments
  • amyloid beta-protein (1-42)