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Structural insights into the membrane-anchoring mechanism of a cholesterol-dependent cytolysin

Rajesh Ramachandran1, Alejandro P Heuck, Rodney K Tweten

  • 1Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.

Nature Structural Biology
|October 9, 2002
PubMed

Insights

Perfringolysin O (PFO) domain 4 binds cholesterol in membranes. Its structure reveals limited bilayer interaction for initial toxin binding and pore formation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Membrane Biophysics

Background:

  • Perfringolysin O (PFO) is a cytolytic toxin from Clostridium perfringens that creates pores in cell membranes.
  • Domain 4 (D4) of PFO is crucial for initial membrane interaction and cholesterol recognition.

Purpose of the Study:

  • To determine the topography of PFO's Domain 4 in its membrane-inserted oligomeric state.
  • To elucidate the role of D4's interaction with the membrane bilayer in PFO's cytolytic mechanism.

Main Methods:

  • Utilized multiple independent fluorescence techniques.
  • Investigated the structure and orientation of D4 within cholesterol-containing membranes.

Main Results:

  • Only the hydrophobic loops at the tip of the D4 beta-sandwich interact with the membrane interior.
  • The majority of D4 extends from the membrane surface, with minimal contact between adjacent monomers.
  • Limited D4-bilayer interaction is sufficient for cholesterol binding and initial PFO membrane association.

Conclusions:

  • PFO's Domain 4 undergoes limited interaction with the membrane bilayer for initial binding and cholesterol recognition.
  • D4 acts as a pivotal point for structural rearrangements during the formation of the transmembrane beta-barrel.
  • Understanding PFO's D4 topography provides insights into toxin pore formation mechanisms.

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