pH dependent insertion of a diphtheria toxin B fragment peptide into the lipid membrane: a conformational analysis

Biochem Biophys Res Commun. 1986 Apr 14;136(1):160-8. doi: 10.1016/0006-291x(86)90890-9.

Abstract

A peptide of diphtheria toxin B fragment (residues 147-266) has been shown to induce pore formation in lipid bilayer membranes at low pH. Such an effect was obtained at a much lower extent or not at all at pH = 7. The region localized between residues 225 and 246 is highly hydrophobic (27.3% polarity) and characterized by a high concentration of proline residues. Since proline cis-trans isomerization is highly sensitive to the pH of the medium, we investigated the capability of the cis and trans isomers to penetrate into the lipid matrix. Obviously, the cis-trans isomerization of proline 242 and 245, assumed to be imposed by a low pH, uncovers the hydrophobic region and induces its insertion into a lipid layer of dipalmitoylphosphatidylcholine. The lipid matrix destabilization resulting from this process could promote the penetration into the lipid bilayer of an amphipatic structure (153-178) similar to the transverse lipid associating domains of membrane proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diphtheria Toxin / metabolism*
  • Hydrogen-Ion Concentration*
  • Lipid Bilayers / metabolism*
  • Models, Molecular*
  • Peptide Fragments / metabolism
  • Proline
  • Pulmonary Surfactants

Substances

  • Diphtheria Toxin
  • Lipid Bilayers
  • Peptide Fragments
  • Pulmonary Surfactants
  • diphtheria toxin fragment B
  • Proline