title: Essential role of domain 4 of pneumolysin from Streptococcus pneumoniae in cytolytic activity as determined by truncated proteins.
abstract: Pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae, is one of the members of thiol-activated cytolysins (TACYs) consisting of four domains. TACYs commonly bind to membrane cholesterol and oligomerize to form transmembrane pore. We have constructed full-length and various truncated PLYs to study the role of domains of PLY in the cytolytic activity. Full-length PLY had binding ability to both cell membrane and immobilized cholesterol. A truncated PLY which comprised only domain 4 molecule, the C-terminal domain of PLY, sustained the binding ability to cell membrane and cholesterol, whereas domain 1-3 molecule had no binding ability to them. Furthermore, the domain 4 molecule inhibited both the membrane binding and the hemolytic activity of full-length PLY. Accordingly, the present results provided the direct evidence that domain 4 was essential for the initial binding to membrane cholesterol and the interaction led to the subsequent membrane damage process.
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Baba
authors.forename: I
authors.initials: I
authors.lastname: Kawamura
authors.forename: C
authors.initials: C
authors.lastname: Kohda
authors.forename: T
authors.initials: T
authors.lastname: Nomura
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: T
authors.initials: T
authors.lastname: Kimoto
authors.forename: I
authors.initials: I
authors.lastname: Watanabe
authors.forename: S
authors.initials: S
authors.lastname: Ichiyama
authors.forename: M
authors.initials: M
authors.lastname: Mitsuyama
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002855:Chromatography, Thin Layer; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism; D006461:Hemolysis; D008024:Ligands; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D012756:Sheep; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D013301:Streptolysins / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D011994:Recombinant Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D002784:Cholesterol