title: A new model for pore formation by cholesterol-dependent cytolysins.
abstract: Cholesterol Dependent Cytolysins (CDCs) are important bacterial virulence factors that form large (200-300 Å) membrane embedded pores in target cells. Currently, insights from X-ray crystallography, biophysical and single particle cryo-Electron Microscopy (cryo-EM) experiments suggest that soluble monomers first interact with the membrane surface via a C-terminal Immunoglobulin-like domain (Ig; Domain 4). Membrane bound oligomers then assemble into a prepore oligomeric form, following which the prepore assembly collapses towards the membrane surface, with concomitant release and insertion of the membrane spanning subunits. During this rearrangement it is proposed that Domain 2, a region comprising three β-strands that links the pore forming region (Domains 1 and 3) and the Ig domain, must undergo a significant yet currently undetermined, conformational change. Here we address this problem through a systematic molecular modeling and structural bioinformatics approach. Our work shows that simple rigid body rotations may account for the observed collapse of the prepore towards the membrane surface. Support for this idea comes from analysis of published cryo-EM maps of the pneumolysin pore, available crystal structures and molecular dynamics simulations. The latter data in particular reveal that Domains 1, 2 and 4 are able to undergo significant rotational movements with respect to each other. Together, our data provide new and testable insights into the mechanism of pore formation by CDCs.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Melbourne, Victoria, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria, Australia.
authors.forename: Cyril F
authors.initials: CF
authors.lastname: Reboul
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Melbourne, Victoria, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria, Australia.
authors.forename: James C
authors.initials: JC
authors.lastname: Whisstock
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Melbourne, Victoria, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria, Australia; Department of Microbiology, Monash University, Clayton Campus, Melbourne, Victoria, Australia.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Dunstone
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D001427:Bacterial Toxins / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002784:Cholesterol; D056004:Molecular Dynamics Simulation; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D052899:Pore Forming Cytotoxic Proteins; D002784:Cholesterol