title: Molecular basis of transmembrane beta-barrel formation of staphylococcal pore-forming toxins.
abstract: Pathogenic bacteria secrete pore-forming toxins (PFTs) to attack target cells. PFTs are expressed as water-soluble monomeric proteins, which oligomerize into nonlytic prepore intermediates on the target cell membrane before forming membrane-spanning pores. Despite a wealth of biochemical data, the lack of high-resolution prepore structural information has hampered understanding of the β-barrel formation process. Here, we report crystal structures of staphylococcal γ-haemolysin and leucocidin prepores. The structures reveal a disordered bottom half of the β-barrel corresponding to the transmembrane region, and a rigid upper extramembrane half. Spectroscopic analysis of fluorescently labelled mutants confirmed that the prepore is distinct from the pore within the transmembrane region. Mutational analysis also indicates a pivotal role for the glycine residue located at the lipid-solvent interface as a 'joint' between the two halves of the β-barrel. These observations suggest a two-step transmembrane β-barrel pore formation mechanism in which the upper extramembrane and bottom transmembrane regions are formed independently.
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Yamashita
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Takaki
authors.initials: T
authors.lastname: Sugawara
authors.affiliation: Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
authors.forename: Miyu
authors.initials: M
authors.lastname: Takeshita
authors.affiliation: Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kaneko
authors.affiliation: Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, Yurigaoka 4-10-1, Natori 981-1295, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kamio
authors.affiliation: 1] Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan [2] Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
authors.affiliation: 1] Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan [2] Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: 1] Graduate School of Life Sciences, Hokkaido University, Sapporo 060-0810, Japan [2] Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Min
authors.initials: M
authors.lastname: Yao
mesh_terms: D000818:Animals; D001120:Arginine / Q000737:chemistry; D001427:Bacterial Toxins / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry; D018360:Crystallography, X-Ray; D004912:Erythrocytes / Q000187:drug effects / Q000382:microbiology; D005998:Glycine / Q000737:chemistry; D006460:Hemolysin Proteins / Q000737:chemistry; D006461:Hemolysis; D006801:Humans; D007956:Leukocidins / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D009154:Mutation; D010743:Phospholipids / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011817:Rabbits; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013211:Staphylococcus aureus / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry
chemical_list: D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D007956:Leukocidins; D008055:Lipids; D010743:Phospholipids; D012997:Solvents; C021091:staphylococcal alpha-toxin; D014364:Tryptophan; D001120:Arginine; D005998:Glycine