title: Identification of novel genomic islands coding for antigenic pilus-like structures in Streptococcus agalactiae.
abstract: We have recently reported the presence of covalently linked pilus-like structures in the human pathogen, Group B Streptococcus (GBS). The pilus operon codes for three proteins which contain the conserved amino acid motif, LPXTG, associated with cell wall-anchored proteins together with two genes coding for sortase enzymes. Analysis of the eight sequenced genomes of GBS has led to the identification of a second, related genomic island of which there are two variants, each containing genes coding for proteins with LPXTG motifs and sortases. Here we show that both variant islands also code for pilus-like structures. Furthermore, we provide a thorough description and characterization of the genomic organization of the islands and the role of each protein in the assembly of the pili. For each pilus, polymerization of one of the three component proteins is essential for incorporation of the other two proteins into the pilus structure. In addition, two sortases are required for complete pilus assembly, each with specificity for one of the pilus components. A component protein of one of the newly identified pili is also a previously identified protective antigen and a second component of this pilus is shown to confer protection against GBS challenge. We propose that pilus-like structures are important virulence factors and potential vaccine candidates.
authors.affiliation: Chiron Vaccines, Via Fiorentina 1, 53100, Siena, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rosini
authors.forename: Cira Daniela
authors.initials: CD
authors.lastname: Rinaudo
authors.forename: Marco
authors.initials: M
authors.lastname: Soriani
authors.forename: Peter
authors.initials: P
authors.lastname: Lauer
authors.forename: Marirosa
authors.initials: M
authors.lastname: Mora
authors.forename: Domenico
authors.initials: D
authors.lastname: Maione
authors.forename: Annarita
authors.initials: A
authors.lastname: Taddei
authors.forename: Isabella
authors.initials: I
authors.lastname: Santi
authors.forename: Claudia
authors.initials: C
authors.lastname: Ghezzo
authors.forename: Cecilia
authors.initials: C
authors.lastname: Brettoni
authors.forename: Scilla
authors.initials: S
authors.lastname: Buccato
authors.forename: Immaculada
authors.initials: I
authors.lastname: Margarit
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.forename: John L
authors.initials: JL
authors.lastname: Telford
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D044404:Genomic Islands / Q000235:genetics* / Q000276:immunology; D006801:Humans; D051379:Mice; D016253:Microscopy, Immunoelectron; D009154:Mutation; D009876:Operon / Q000235:genetics; D013290:Streptococcal Infections / Q000235:genetics / Q000378:metabolism; D013292:Streptococcus agalactiae / Q000235:genetics* / Q000472:pathogenicity / Q000648:ultrastructure; D014774:Virulence / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D036781:Fimbriae Proteins; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases