title: Molecular characterization of a Streptococcus gallolyticus genomic island encoding a pilus involved in endocarditis.
abstract: BACKGROUND
  Streptococcus gallolyticus is a causative agent of infective endocarditis associated with colon cancer. Genome sequence of strain UCN34 revealed the existence of 3 pilus loci (pil1, pil2, and pil3). Pili are long filamentous structures playing a key role as adhesive organelles in many pathogens. The pil1 locus encodes 2 LPXTG proteins (Gallo2178 and Gallo2179) and 1 sortase C (Gallo2177). Gallo2179 displaying a functional collagen-binding domain was referred to as the adhesin, whereas Gallo2178 was designated as the major pilin.
  
  
  METHODS
  S. gallolyticus UCN34, Pil1(+) and Pil1(-), expressing various levels of pil1, and recombinant Lactococcus lactis strains, constitutively expressing pil1, were studied. Polyclonal antibodies raised against the putative pilin subunits Gallo2178 and Gallo2179 were used in immunoblotting and immunogold electron microscopy. The role of pil1 was tested in a rat model of endocarditis.
  
  
  RESULTS
  We showed that the pil1 locus (gallo2179-78-77) forms an operon differentially expressed among S. gallolyticus strains. Short pilus appendages were identified both on the surface of S. gallolyticus UCN34 and recombinant L. lactis-expressing pil1. We demonstrated that Pil1 pilus is involved in binding to collagen, biofilm formation, and virulence in experimental endocarditis.
  
  
  CONCLUSIONS
  This study identifies Pil1 as the first virulence factor characterized in S. gallolyticus.
authors: Unité de Biologie des Bactéries Pathogènes à Gram-Positif, Institut Pasteur, Paris, France.
authors: Camille
authors: C
authors: Danne
authors: José M
authors: JM
authors: Entenza
authors: Adeline
authors: A
authors: Mallet
authors: Romain
authors: R
authors: Briandet
authors: Michel
authors: M
authors: Débarbouillé
authors: Farida
authors: F
authors: Nato
authors: Philippe
authors: P
authors: Glaser
authors: Grégory
authors: G
authors: Jouvion
authors: Philippe
authors: P
authors: Moreillon
authors: Patrick
authors: P
authors: Trieu-Cuot
authors: Shaynoor
authors: S
authors: Dramsi
mesh_terms: D000818:Animals; D018441:Biofilms; D003094:Collagen / Q000378:metabolism; D004696:Endocarditis / Q000382:microbiology*; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics* / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism; D056426:Genetic Loci / Q000235:genetics; D044404:Genomic Islands / Q000235:genetics*; D009876:Operon / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D037521:Virulence Factors; D036781:Fimbriae Proteins; D003094:Collagen