title: LuxS and expression of virulence factors in Streptococcus intermedius.
abstract: OBJECTIVE
  Autoinducer-2 (AI-2) is used by several bacteria in quorum-sensing signaling and is a product of LuxS. The aim was to investigate the effect of LuxS mutation on expression of Streptococcus intermedius virulence factors.
  
  
  METHODS
  S. intermedius mutants were constructed by insertion inactivation or gene deletion. Real time RT-PCR was used to assess transcription of pas, ily and hyl. Hyaluronidase and intermedilysin activities were measured biochemically.
  
  
  RESULTS
  The results indicated that disruption of luxS in S. intermedius may affect hyaluronidase and intermedilysin gene expressions. No difference in antigen I/II expression was observed. Biochemical methods showed a five-fold decrease in hemolytic activity of the luxS mutant; however, secreted hyaluronidase activity was unaffected. The AI-2 precursor 4,5-dihydroxy-2,3-pentanedione complemented lack of AI-2 production by the mutant thus restoring hemolytic activity.
  
  
  CONCLUSIONS
  We suggest that AI-2 communication is involved in intermedilysin expression.
authors.affiliation: Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway. ddasilva@odont.uio.no
authors.forename: D
authors.initials: D
authors.lastname: Pecharki
authors.forename: F C
authors.initials: FC
authors.lastname: Petersen
authors.forename: A Aa
authors.initials: AA
authors.lastname: Scheie
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D001427:Bacterial Toxins / Q000032:analysis; D001430:Bacteriocins / Q000032:analysis; D013437:Carbon-Sulfur Lyases / Q000032:analysis* / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D017353:Gene Deletion; D020868:Gene Silencing; D006461:Hemolysis; D006714:Homoserine / Q000031:analogs & derivatives / Q000032:analysis; D006801:Humans; D006821:Hyaluronoglucosaminidase / Q000032:analysis; D007783:Lactones / Q000032:analysis; D008562:Membrane Glycoproteins / Q000032:analysis; D009154:Mutation / Q000235:genetics; D010420:Pentanes / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D034367:Streptococcus intermedius / Q000235:genetics / Q000472:pathogenicity*; D014158:Transcription, Genetic / Q000235:genetics; D037521:Virulence Factors / Q000032:analysis* / Q000235:genetics
chemical_list: C493138:4,5-dihydroxy-2,3-pentanedione; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001430:Bacteriocins; D007783:Lactones; D008562:Membrane Glycoproteins; C091088:N-octanoylhomoserine lactone; D010420:Pentanes; C055764:S-layer proteins; D037521:Virulence Factors; C403910:intermedilysin protein, Streptococcus intermedius; D006714:Homoserine; D006821:Hyaluronoglucosaminidase; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria