title: Novel twin streptolysin S-like peptides encoded in the sag operon homologue of beta-hemolytic Streptococcus anginosus.
abstract: Streptococcus anginosus is a member of the anginosus group streptococci, which form part of the normal human oral flora. In contrast to the pyogenic group streptococci, our knowledge of the virulence factors of the anginosus group streptococci, including S. anginosus, is not sufficient to allow a clear understanding of the basis of their pathogenicity. Generally, hemolysins are thought to be important virulence factors in streptococcal infections. In the present study, a sag operon homologue was shown to be responsible for beta-hemolysis in S. anginosus strains by random gene knockout. Interestingly, contrary to pyogenic group streptococci, beta-hemolytic S. anginosus was shown to have two tandem sagA homologues, encoding streptolysin S (SLS)-like peptides, in the sag operon homologue. Gene deletion and complementation experiments revealed that both genes were functional, and these SLS-like peptides were essential for beta-hemolysis in beta-hemolytic S. anginosus. Furthermore, the amino acid sequence of these SLS-like peptides differed from that of the typical SLS of S. pyogenes, especially in their propeptide domain, and an amino acid residue indicated to be important for the cytolytic activity of SLS in S. pyogenes was deleted in both S. anginosus homologues. These data suggest that SLS-like peptides encoded by two sagA homologues in beta-hemolytic S. anginosus may be potential virulence factors with a different structure essential for hemolytic activity and/or the maturation process compared to the typical SLS present in pyogenic group streptococci.
authors.affiliation: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, Minamijosanjima-cho, Tokushima, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tabata
authors.forename: Kota
authors.initials: K
authors.lastname: Nakano
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ohkura
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Tomoyasu
authors.forename: Ken
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Robert A
authors.initials: RA
authors.lastname: Whiley
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nagamune
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D055786:Gene Knockout Techniques; D006460:Hemolysin Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D034366:Streptococcus anginosus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D013297:Streptococcus pyogenes / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D013301:Streptolysins / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D013301:Streptolysins; C026050:streptolysin S