Identification of Novel Adhesins from Group B Streptococci by Use of Phage Display Reveals that C5a Peptidase Mediates Fibronectin Binding

Division of Infectious Disease, Children's Hospital and Regional Medical Center and University of Washington, Seattle 98105, USA.
Infection and Immunity (Impact Factor: 3.73). 07/2002; 70(6):2869-76. DOI: 10.1128/IAI.70.6.2869-2876.2002
Source: PubMed


Group B streptococci (GBS) are a major cause of pneumonia, sepsis, and meningitis in newborns and infants. GBS initiate infection of the lung by colonizing mucosal surfaces of the respiratory tract; adherence of the bacteria to host cells is presumed to be the initial step in and prerequisite for successful colonization (G. S. Tamura, J. M. Kuypers, S. Smith, H. Raff, and C. E. Rubens, Infect. Immun. 62:2450-2458, 1994). We have performed a genome-wide screen to identify novel genes of GBS that mediate adherence to fibronectin. A shotgun phage display library was constructed from chromosomal DNA of a serotype Ia GBS strain and affinity selected on immobilized fibronectin. DNA sequence analysis of different clones identified 19 genes with homology to known bacterial adhesin genes, virulence genes, genes involved in transport or metabolic processes, and genes with yet-unknown function. One of the isolated phagemid clones showed significant homology to the gene (scpB) for the GBS C5a peptidase, a surface-associated serine protease that specifically cleaves the complement component C5a, a chemotaxin for polymorphonuclear leukocytes. In this work we have demonstrated that affinity-purified recombinant ScpB and a peptide ScpB fragment (ScpB-PDF), similar to the peptide identified in the phagemid, bound fibronectin in a concentration-dependent manner. Adherence assays to fibronectin were performed, comparing an isogenic scpB mutant to the wild-type strain. Approximately 50% less binding was observed with the mutant than with the wild-type strain. The mutant phenotype could be fully restored by in trans complementation of the mutant with the cloned wild-type scpB gene, providing further evidence for the role of ScpB in fibronectin adherence. Our results suggest that C5a peptidase is a bifunctional protein, which enzymatically cleaves C5a and mediates adherence to fibronectin. Since binding of fibronectin has been implicated in attachment and invasion of eukaryotic cells by streptococci, our results may imply a second important role for this surface protein in the pathogenesis of GBS infections.

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Available from: Christiane Beckmann, Apr 19, 2014
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    • "С5а пептидаза специфически расщепляет С5а фракцию комплемента и, как следствие, препятствует миграции полиморфноядерных лейкоцитов в очаг воспаления[7,19]. Кроме того, было продемонстрировано, что эта клеточносвязанная протеаза обладает свойствами адгезина и инвазина, взаимодействует с фибринектином и непосредственно с эпителиальными клетками человека[6,8]. Интерес к SCPB также обусловлен ее высокой консервативностью и распространен- ностью[9]. "

    Full-text · Article · Jul 2014
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    • "ScpB mediates cleavage of the chemotactic component C5a and binding to human immobilized fibronectin, a component of the extracellular matrix. ScpB also plays a role in the invasion of epithelial cells (Beckmann et al., 2002; Cheng et al., 2002). The surface-associated lipoprotein Lmb mediates binding of S. agalactiae to human laminin, a major component of the basement membrane, and promotes invasion of human brain microvascular endothelial cells (Spellerberg et al., 1999b; Tenenbaum et al., 2007). "
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    ABSTRACT: We have referenced and described Streptococcus agalactiae transposable elements encoding DDE transposases. These elements belong to nine families of insertion sequences (IS) and to a family of conjugative transposons (TnGBS). An overview of the physiological impact of the insertion of all these elements is provided. DDE-transposable elements affect S. agalactiae in various aspects of its capability of adaptation to various environments and modulate the expression of several virulence genes, the scpB-lmB genomic region and the genes involved in capsule expression and hemolysin transport being even the targets of several different mobile elements. The referenced mobile elements modify S. agalactiae behavior by transferring new gene(s) to its genome, by modifying neighboring gene-expression at their integration site, or by promoting genomic rearrangements. Transposition of some of these elements occurs in vivo, suggesting that by dynamically regulating some adaptation and/or virulence genes, they improve the ability of S. agalactiae to reach subsequently different niches within their host and ensure the "success" of the infectious process.
    Preview · Article · Apr 2014 · Microbiology
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    • "Bacterial surface proteins have been studied extensively in pathogenic bacteria over the last several decades, demonstrating their role in host colonization and cell invasion as well as very sophisticated manipulation of the host immune response pathways that often neutralize microbial-pattern-induced signaling pathways (Patti et al. 1994; Beckmann et al. 2002; Selbach and Backert 2005; Lilic et al. 2006; Luck et al. 2006; Timmer et al. 2006; Eskan et al. 2007; Gillen et al. 2008; Kulkarni et al. 2009; McGhie et al. 2009). Together with the diversity of nonprotein surface molecules and structures (cell wall peptidoglycan, lipotheicoic acid, and exopolysaccharides), surface and secreted proteins determine the overall interaction of a pathogen with the host and the outcomes of the pathogen colonization (Grandel and Grimminger 2003; Boltana et al. 2011; Elberse et al. 2011; Hao et al. 2011; Tuanyok et al. 2012). "
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