CryoEM structures of membrane pore and prepore complex reveal cytolytic mechanism of Pneumolysin.
Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor ofStreptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain 3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel. The apolar outer barrel surface with large sidechains is immersed in the lipid bilayer, while the inner barrel surface is highly charged. Comparison of the cryoEM pore complex to the prepore structure obtained by electron cryo-tomography and the x-ray structure of the soluble form reveals the detailed mechanisms by which the toxin monomers insert into the lipid bilayer to perforate the target membrane.
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Katharina
K
van Pee
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Alexander
A
Neuhaus
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Edoardo
E
D'Imprima
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Deryck J
DJ
Mills
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Werner
0000-0002-2013-4810
W
Kühlbrandt
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Özkan
0000-0003-3659-2805
Ö
Yildiz
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D002462:Cell Membrane / Q000187:drug effects* / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D004912:Erythrocytes / Q000187:drug effects; D008958:Models, Molecular; D012756:Sheep; D013301:Streptolysins / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae
X-ray crystallography; biophysics; cholesterol-dependent cytolysin (CDC); electron cryo-microscopy (cryoEM); electron cryo-tomography (cryoET); infectious disease; membrane pore; microbiology; pore-forming toxin; structural biology