title: A streptolysin S homologue is essential for β-haemolytic Streptococcus constellatus subsp. constellatus cytotoxicity.
abstract: Streptococcus constellatus is a member of the Anginosus group streptococci (AGS) and primarily inhabits the human oral cavity. S. constellatus is composed of three subspecies: S. constellatus subsp. constellatus (SCC), S. constellatus subsp. pharyngis and the newly described subspecies S. constellatus subsp. viborgensis. Although previous studies have established that SCC contains β-haemolytic strains, the factor(s) responsible for β-haemolysis in β-haemolytic SCC (β-SCC) has yet to be clarified. Recently, we discovered that a streptolysin S (SLS) homologue is the β-haemolytic factor of β-haemolytic Streptococcus anginosus subsp. anginosus (β-SAA), another member of the AGS. Furthermore, because previous studies have suggested that other AGS species, except for Streptococcus intermedius, do not possess a haemolysin(s) belonging to the family of cholesterol-dependent cytolysins, we hypothesized that, as with β-SAA, the SLS homologue is the β-haemolytic factor of β-SCC, and therefore aimed to investigate and characterize the haemolytic factor of β-SCC in the present study. PCR amplification revealed that all of the tested β-SCC strains were positive for the sagA homologue of SCC (sagA(SCC)). Further investigations using β-SCC strain W277 were conducted to elucidate the relationship between sagA(SCC) and β-haemolysis by constructing sagA(SCC) deletion mutants, which completely lost β-haemolytic activity. This loss of β-haemolytic activity was restored by trans-complementation of sagA(SCC). Furthermore, a co-cultivation assay established that the cytotoxicity of β-SCC was clearly dependent on the presence of sagA(SCC). These results demonstrate that sagA(SCC) is the factor responsible for β-SCC β-haemolysis and cytotoxicity.
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tabata
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Maya
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Nakano
authors.affiliation: Department of Infection Control Science, Faculty of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kikuchi
authors.affiliation: Department of Clinical and Diagnostic Oral Sciences, Institute of Dentistry, Bart's and The London School of Medicine and Dentistry, Queen Mary University of London, Turner Street, London E1 2AD, UK.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Whiley
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minamitamagaki-cho, Suzuka, Mie 513-0816, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ohkura
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Tomoyasu
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minamijosanjima-cho, Tokushima, Tokushima 770-8506, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagamune
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006801:Humans; D008969:Molecular Sequence Data; D009055:Mouth / Q000382:microbiology; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013290:Streptococcal Infections / Q000382:microbiology; D034365:Streptococcus constellatus / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D013301:Streptolysins / Q000235:genetics / Q000633:toxicity*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D013301:Streptolysins; C026050:streptolysin S