title: Irreversible loss of membrane-binding activity of Listeria-derived cytolysins in non-acidic conditions: a distinct difference from allied cytolysins produced by other Gram-positive bacteria.
abstract: Listeriolysin O (LLO), a member of the cholesterol-dependent cytolysin (CDC) family, is a major virulence factor of Listeria monocytogenes and contributes to bacterial escape from intracellular killing of macrophages. LLO is activated under weakly acidic conditions; however, the molecular mechanism of this pH-dependent expression of cytolytic activity of LLO is poorly understood. In this study, CDCs including LLO, ivanolysin O (ILO), seeligeriolysin O (LSO), pneumolysin (PLY), streptolysin O (SLO) and perfringolysin O (PFO) were prepared as recombinant proteins and examined for their functional changes after treatment under various pH conditions. Haemolytic and membrane cholesterol-binding activities were not affected in PLY, SLO and PFO at any pH examined. By contrast, all the Listeria-derived cytolysins, LLO, ILO and LSO, were active only at an acidic pH and rapidly inactivated under neutral or alkaline conditions. Once inactivated, LLO could not be reactivated even by a downward pH shift. The hydrophobicity of LLO treated at neutral or alkaline pH was increased. These data suggested that the pH-dependent loss of cytolytic activity appeared to be due to irreversible structural changes of domain 4 that resulted in the loss of target membrane cholesterol binding.
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kawamura
authors.affiliation: Department of Microbiology and Immunology, Showa University School of Medicine, Tokyo 142-8555, Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Kohda
authors.affiliation: Department of Infectious Diseases, Nagoya University School of Medicine, Nagoya 466-8550, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Baba
authors.affiliation: Department of Respiratory Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.|Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Terumi
authors.initials: T
authors.lastname: Kimoto
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Watanabe
authors.affiliation: Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Mitsuyama
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D003603:Cytotoxins / Q000276:immunology / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000502:physiology; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D002784:Cholesterol; C038705:hlyA protein, Listeria monocytogenes