Binding of prion proteins to lipid membranes

Biochem Biophys Res Commun. 2004 Jan 16;313(3):559-67. doi: 10.1016/j.bbrc.2003.12.004.

Abstract

A key molecular event in prion diseases is the conversion of the normal cellular form of the prion protein (PrPC) to an aberrant form known as the scrapie isoform, PrPSc. Under normal physiological conditions PrPC is attached to the outer leaflet of the plasma membrane via a GPI-anchor. It has been proposed that a direct interaction between PrP and lipid membranes could be involved in the conversion of PrPC to its disease-associated corrupted conformation, PrPSc. Recombinant PrP can be refolded into an alpha-helical structure, designated alpha-PrP isoform, or into beta-sheet-rich states, designated beta-PrP isoform. The current study investigates the binding of recombinant PrP isoforms to model lipid membranes using surface plasmon resonance spectroscopy. The binding of alpha- and beta-PrP to negatively charged lipid membranes of POPG, zwitterionic membranes of DPPC, and model raft membranes composed of DPPC, cholesterol, and sphingomyelin is compared at pH 7 and 5, to simulate the environment at the plasma membrane and within endosomes, respectively. It is found that PrP binds strongly to lipid membranes. The strength of the association of PrP with lipid membranes depends on the protein conformation and pH, and involves both hydrophobic and electrostatic lipid-protein interactions. Competition binding measurements established that the binding of alpha-PrP to lipid membranes follows a decreasing order of affinity to POPG>DPPC>rafts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / chemistry
  • Animals
  • Binding, Competitive
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism*
  • Circular Dichroism
  • Cricetinae
  • Dose-Response Relationship, Drug
  • Endosomes / metabolism
  • Hydrogen-Ion Concentration
  • Inhibitory Concentration 50
  • Lipid Bilayers / chemistry
  • Lipids / chemistry*
  • Membrane Microdomains / chemistry
  • Mesocricetus
  • PrPC Proteins / metabolism*
  • PrPSc Proteins / chemistry*
  • Protein Binding
  • Protein Conformation
  • Protein Isoforms
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Sodium Chloride / pharmacology
  • Sphingomyelins / chemistry
  • Surface Plasmon Resonance
  • Time Factors

Substances

  • Lipid Bilayers
  • Lipids
  • PrPC Proteins
  • PrPSc Proteins
  • Protein Isoforms
  • Recombinant Proteins
  • Sphingomyelins
  • Sodium Chloride
  • Alkaline Phosphatase