title: The domains of a cholesterol-dependent cytolysin undergo a major FRET-detected rearrangement during pore formation.
abstract: FRET measurements were used to determine the domain-specific topography of perfringolysin O, a pore-forming toxin, on a membrane surface at different stages of pore formation. The data reveal that the elongated toxin monomer binds stably to the membrane in an "end-on" orientation, with its long axis approximately perpendicular to the plane of the membrane bilayer. This orientation is largely retained even after monomer association to form an oligomeric prepore complex. The domain 3 (D3) polypeptide segments that ultimately form transmembrane beta-hairpins remain far above the membrane surface in both the membrane-bound monomer and prepore oligomer. Upon pore formation, these segments enter the bilayer, whereas D1 moves to a position that is substantially closer to the membrane. Therefore, the extended D2 beta-structure that connects D1 to membrane-bound D4 appears to bend or otherwise reconfigure during the prepore-to-pore transition of the perfringolysin O oligomer.
authors.affiliation: Department of Biochemistry, Texas A&M University, College Station, TX 77843-1114, USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Ramachandran
authors.forename: Rodney K
authors.initials: RK
authors.lastname: Tweten
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Johnson
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000502:physiology*; D003603:Cytotoxins / Q000737:chemistry / Q000378:metabolism*; D005454:Fluorescence Polarization; D031541:Fluorescence Resonance Energy Transfer; D006460:Hemolysin Proteins; D008958:Models, Molecular; D017434:Protein Structure, Tertiary / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D006460:Hemolysin Proteins; C020452:Clostridium perfringens theta-toxin