Identification of novel genomic islands coding for antigenic pilus‐like structures in Streptococcus agalactiae

• Published in: Molecular microbiology 2006-07, Vol.61 (1), p.126-141
• Main Authors: Rosini, Roberto, Rinaudo, Cira Daniela, Soriani, Marco, Lauer, Peter, Mora, Marirosa, Maione, Domenico, Taddei, Annarita, Santi, Isabella, Ghezzo, Claudia, Brettoni, Cecilia, Buccato, Scilla, Margarit, Immaculada, Grandi, Guido, Telford, John L.
• Format: Article
• Language: English
• Subjects: Adhesins, Bacterial - genetics; Adhesins, Bacterial - immunology; Adhesins, Bacterial - metabolism; Amino Acid Motifs - genetics; Amino Acid Sequence; Aminoacyltransferases - genetics; Aminoacyltransferases - metabolism; Aminoacyltransferases - physiology; Animals; Antigens, Bacterial - genetics; Antigens, Bacterial - metabolism; Antigens, Bacterial - physiology; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacterial Proteins - physiology; Bacteriology; Biological and medical sciences; Cell Wall - metabolism; Cysteine Endopeptidases - genetics; Cysteine Endopeptidases - metabolism; Cysteine Endopeptidases - physiology; Female; Fimbriae Proteins - genetics; Fimbriae Proteins - immunology; Fimbriae Proteins - metabolism; Fimbriae, Bacterial - genetics; Fimbriae, Bacterial - metabolism; Fimbriae, Bacterial - ultrastructure; Fundamental and applied biological sciences. Psychology; Genomic Islands - genetics; Genomic Islands - immunology; Humans; Mice; Microbiology; Microorganisms; Microscopy, Immunoelectron; Miscellaneous; Mutation; Operon - genetics; Pathogens; Proteins; Streptococcal Infections - genetics; Streptococcal Infections - metabolism; Streptococcus agalactiae; Streptococcus agalactiae - genetics; Streptococcus agalactiae - pathogenicity; Streptococcus agalactiae - ultrastructure; Virulence - genetics
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2006.05225.x

Summary 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.