title: Characterization of pneumolysin from Streptococcus pneumoniae, interacting with carbohydrate moiety and cholesterol as a component of cell membrane.
abstract: The cytolytic mechanism of cholesterol-dependent cytolysins (CDCs) requires the presence of cholesterol in the target cell membrane. Membrane cholesterol was thought to serve as the common receptor for these toxins, but not all CDCs require cholesterol for binding. One member of this toxin family, pneumolysin (PLY) is a major virulence factor of Streptococcus pneumoniae, and the mechanism via which PLY binds to its putative receptor or cholesterol on the cell membrane is still poorly understood. Here, we demonstrated that PLY interacted with carbohydrate moiety and cholesterol as a component of the cell membrane, using the inhibitory effect of hemolytic activity. The hemolytic activity of PLY was inhibited by cholesterol-MβCD, which is in a 3β configuration at the C3-hydroxy group, but is not in a 3α-configuration. In the interaction between PLY and carbohydrate moiety, the mannose showed a dose-dependent increase in the inhibition of PLY hemolytic activity. The binding ability of mannose with truncated PLYs, as determined by the pull-down assay, showed that mannose might favor binding to domain 4 rather than domains 1-3. These studies provide a new model for the mechanism of cellular recognition by PLY, as well as a foundation for future investigations into whether non-sterol molecules can serve as receptors for other members of the CDC family of toxins.
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Republic of Korea.
authors.forename: Jong Eun
authors.initials: JE
authors.lastname: Lim
authors.forename: Seong Ah
authors.initials: SA
authors.lastname: Park
authors.forename: Seoung Min
authors.initials: SM
authors.lastname: Bong
authors.forename: Young Min
authors.initials: YM
authors.lastname: Chi
authors.forename: Ki Seog
authors.initials: KS
authors.lastname: Lee
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D002478:Cells, Cultured; D002784:Cholesterol / Q000737:chemistry*; D004910:Erythrocyte Membrane / Q000737:chemistry*; D004912:Erythrocytes / Q000737:chemistry; D005690:Galactose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D006801:Humans; D008358:Mannose / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013301:Streptolysins / Q000737:chemistry* / Q000235:genetics; D014867:Water
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D014867:Water; D002784:Cholesterol; D005947:Glucose; D008358:Mannose; D005690:Galactose