title: Analysis of the Streptococcus agalactiae exoproteome.
abstract: The two-component regulatory system CovRS is the main regulator of virulence gene expression in Group B Streptococcus (GBS), the leading cause of invasive infections in neonates. In this study we analyzed by mass spectrometry the GBS extracellular protein complex (i.e. the exoproteome) of NEM316 wild-type (WT) strain and its isogenic covRS deletion mutant (ΔcovRS). A total of 53 proteins, 49 of which had classical secretion signals, were identified: 12 were released by both strains while 21 and 20 were released exclusively by WT and ΔcovRS strains, respectively. In addition to known surface proteins, we detected here unstudied cell-wall associated proteins and/or orthologs of putative virulence factors present in other pathogenic streptococci. While the functional role of these proteins remains to be elucidated, our data suggest that the analysis of the exoproteome of bacterial pathogens under different gene expression conditions may be a powerful tool for the rapid identification of novel virulence factors and vaccine candidates.
  
  
  CONCLUSIONS
  We believe that this manuscript will be of interest to Journal of Proteomics readers since the paper describes the identification of several putative virulence factors and vaccine candidates of the group B streptococcus, an important pathogen, using a simple proteomics strategy involving LC-MS analysis of culture supernatants obtained from two strains with divergent gene expression patterns. This technique provided the most comprehensive inventory of extracellular proteins obtained from a single streptococcal species thus far. The approach described has the added benefit of being easily applicable to a large number of different strains, making it ideal for the identification of conserved vaccine candidates.
authors.affiliation: Metchnikoff Laboratory, University of Messina, Messina I-98125, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Papasergi
authors.forename: Roberta
authors.initials: R
authors.lastname: Galbo
authors.forename: Veronica
authors.initials: V
authors.lastname: Lanza-Cariccio
authors.forename: Maria
authors.initials: M
authors.lastname: Domina
authors.forename: Giacomo
authors.initials: G
authors.lastname: Signorino
authors.forename: Carmelo
authors.initials: C
authors.lastname: Biondo
authors.forename: Ida
authors.initials: I
authors.lastname: Pernice
authors.forename: Claire
authors.initials: C
authors.lastname: Poyart
authors.forename: Patrick
authors.initials: P
authors.lastname: Trieu-Cuot
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Teti
authors.forename: Concetta
authors.initials: C
authors.lastname: Beninati
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013058:Mass Spectrometry; D020543:Proteome / Q000276:immunology / Q000378:metabolism*; D022541:Streptococcal Vaccines / Q000235:genetics / Q000276:immunology; D013292:Streptococcus agalactiae / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D022541:Streptococcal Vaccines; D037521:Virulence Factors
keywords: Bacterial infections; Mass spectrometry; Proteomics; Virulence factors