title: Environmental acidification drives S. pyogenes pilus expression and microcolony formation on epithelial cells in a FCT-dependent manner.
abstract: Group A Streptococcus (GAS, Streptococcus pyogenes) is a gram-positive human pathogen responsible for a diverse variety of diseases, including pharyngitis, skin infections, invasive necrotizing fasciitis and autoimmune sequelae. We have recently shown that GAS cell adhesion and biofilm formation is associated with the presence of pili on the surface of these bacteria. GAS pilus proteins are encoded in the FCT (Fibronectin-Collagen-T antigen) genomic region, of which nine different variants have been identified so far. In the present study we undertook a global analysis of GAS isolates representing the majority of FCT-variants to investigate the effect of environmental growth conditions on their capacity to form multicellular communities. For FCT-types 2, 3, 5 and 6 and a subset of FCT-4 strains, we observed that acidification resulting from fermentative sugar metabolism leads to an increased ability of the bacteria to form biofilm on abiotic surfaces and microcolonies on epithelial cells. The higher biofilm forming capacity at low environmental pH was directly associated with an enhanced expression of the genes encoding the pilus components and of their transcription regulators. The data indicate that environmental pH affects the expression of most pilus types and thereby the formation of multicellular cell-adhering communities that assist the initial steps of GAS infection.
authors.affiliation: Novartis Vaccines and Diagnostics, Siena, Italy.
authors.forename: Andrea G O
authors.initials: AG
authors.lastname: Manetti
authors.forename: Thomas
authors.initials: T
authors.lastname: Köller
authors.forename: Marco
authors.initials: M
authors.lastname: Becherelli
authors.forename: Scilla
authors.initials: S
authors.lastname: Buccato
authors.forename: Bernd
authors.initials: B
authors.lastname: Kreikemeyer
authors.forename: Andreas
authors.initials: A
authors.lastname: Podbielski
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.forename: Immaculada
authors.initials: I
authors.lastname: Margarit
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D045744:Cell Line, Tumor; D003094:Collagen / Q000235:genetics; D004847:Epithelial Cells / Q000382:microbiology*; D005353:Fibronectins / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D018613:Microscopy, Confocal; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity; D013297:Streptococcus pyogenes / Q000145:classification / Q000235:genetics / Q000502:physiology*
chemical_list: D000942:Antigens, Bacterial; D005353:Fibronectins; D036781:Fimbriae Proteins; D003094:Collagen; D005947:Glucose