title: Membrane-dependent conformational changes initiate cholesterol-dependent cytolysin oligomerization and intersubunit beta-strand alignment.
abstract: Cholesterol-dependent cytolysins are bacterial protein toxins that bind to cholesterol-containing membranes, form oligomeric complexes and insert into the bilayer to create large aqueous pores. Membrane-dependent structural rearrangements required to initiate the oligomerization of perfringolysin O monomers have been identified, as have the monomer-monomer interaction surfaces, using site-specific mutagenesis, disulfide trapping and multiple fluorescence techniques. Upon binding to the membrane, a structural element in perfringolysin O moves to expose the edge of a previously hidden beta-strand that forms the monomer-monomer interface and is required for oligomer assembly. The beta-strands that form the interface each contain a single aromatic residue, and these aromatics appear to stack, thereby aligning the transmembrane beta-hairpins of adjacent monomers in the proper register for insertion. Collectively, these data reveal a novel membrane binding-dependent mechanism for regulating cytolysin monomer-monomer association and pore formation.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, 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; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003603:Cytotoxins / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D006460:Hemolysin Proteins; D008051:Lipid Bilayers / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008958:Models, Molecular; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D003603:Cytotoxins; D004220:Disulfides; D006460:Hemolysin Proteins; D008051:Lipid Bilayers; D008081:Liposomes; D010455:Peptides; D014867:Water; D014443:Tyrosine; C020452:Clostridium perfringens theta-toxin; D004247:DNA; D002784:Cholesterol; D005998:Glycine