title: 2-Methyl-2,4-pentanediol induces spontaneous assembly of staphylococcal α-hemolysin into heptameric pore structure.
abstract: Staphylococcal α-hemolysin is expressed as a water-soluble monomeric protein and assembles on membranes to form a heptameric pore structure. The heptameric pore structure of α-hemolysin can be prepared from monomer in vitro only in the presence of deoxycholate detergent micelles, artificially constructed phospholipid bilayers, or erythrocytes. Here, we succeeded in preparing crystals of the heptameric form of α-hemolysin without any detergent but with 2-methyl-2,4-pentanediol (MPD), and determined its structure. The structure of the heptameric pore was similar to that reported previously. In the structure, two molecules of MPD were bound around Trp179, around which phospholipid head groups were bound in the heptameric pore structure reported previously. Size exclusion chromatography showed that α-hemolysin did not assemble spontaneously even when stored for 1 year. SDS-PAGE analysis revealed that, among the compounds in the crystallizing buffer, MPD could induce heptamer formation. The concentration of MPD that most efficiently induced oligomerization was between 10 and 30%. Based on these observations, we propose MPD as a reagent that can facilitate heptameric pore formation of α-hemolysin without membrane binding.
authors.affiliation: Creative Research Institution Sousei, Hokkaido University, Sapporo 001-0021, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Nagisa
authors.initials: N
authors.lastname: Hirano
authors.forename: Jun
authors.initials: J
authors.lastname: Kaneko
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kamio
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D003460:Crystallization; D006018:Glycols / Q000737:chemistry*; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000378:metabolism; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D001427:Bacterial Toxins; D006018:Glycols; D006460:Hemolysin Proteins; D021122:Protein Subunits; C021091:staphylococcal alpha-toxin; C011480:hexylene glycol