title: The diversity of receptor recognition in cholesterol-dependent cytolysins.
abstract: Cholesterol-dependent cytolysins (CDCs) are bacterial pore-forming toxins secreted mainly by pathogenic Gram-positive bacteria. CDCs generally recognize and bind to membrane cholesterol to create pores and lyse target cells. However, in contrast to typical CDCs such as streptolysin O, several atypical CDCs have been reported. The first of these was intermedilysin, which is secreted by Streptococcus intermedius and has human cell-specificity, human CD59 (huCD59) being its receptor. In the study reported here, the diversity of receptor recognition among CDCs was investigated and multi-receptor recognition characteristics were identified within this toxin family. Streptococcus mitis-derived human platelet aggregation factor (Sm-hPAF) secreted by S. mitis strain Nm-65 isolated from a patient with Kawasaki disease was previously shown to hemolyze erythrocytes in a species-dependent manner, its maximum activity being in human cells. In the present study, it was found that Sm-hPAF recognizes both membrane cholesterol and huCD59 as receptors for triggering pore-formation. Moreover, vaginolysin (VLY) of Gardnerella vaginalis showed similar characteristics to Sm-hPAF regarding receptor recognition. On the basis of the results presented here, the mode of receptor recognition of CDCs can be categorized into the following three groups: (i) Group I, comprising typical CDCs with high affinity to cholesterol and no or very little affinity to huCD59; (ii) Group II, including atypical CDCs such as ILY, with no or very little affinity to cholesterol and high affinity to huCD59; and (iii) Group III, which contains atypical CDCs such as Sm-hPAF and VLY with affinity to both cholesterol and huCD59.
authors.affiliation: Department of Biological Science and Technology, Institute of Technology and Science, University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima, 770-8506.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tabata
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ohkura
authors.forename: Yukimasa
authors.initials: Y
authors.lastname: Ohkubo
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Tomoyasu
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ohkuni
authors.forename: Robert A
authors.initials: RA
authors.lastname: Whiley
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagamune
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D003603:Cytotoxins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D013290:Streptococcal Infections / Q000378:metabolism* / Q000382:microbiology; D034367:Streptococcus intermedius / Q000737:chemistry / Q000378:metabolism*; D034361:Streptococcus mitis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D011956:Receptors, Cell Surface; D002784:Cholesterol
keywords: Streptococcus mitis-derived human platelet aggregation factor; cholesterol-dependent cytolysins; receptor recognition; vaginolysin