Assembly and role of pili in group B streptococci

作者：Shaynoor Dramsi, Élise Caliot, Isabelle Bonne, Stéphanie Guadagnini, Marie‐Christine Prévost, Mila Kojadinovic, Lila Lalioui, Claire Poyart, Patrick Trieu‐Cuot · 发表于：Molecular Microbiology · 年份：2006 · DOI：10.1111/j.1365-2958.2006.05190.x · 被引用次数：247 · 研究领域：Biochemical and Structural Characterization、Streptococcal Infections and Treatments、Neonatal and Maternal Infections

Streptococcus agalactiae[group B streptococcus (GBS)] is the leading cause of neonatal pneumonia, sepsis and meningitis. An in silico genome analysis indicated that GBS strain NEM316 encodes five putative sortases, including the major class A sortase enzyme and four class C sortases. The genes encoding the class C sortases are tandemly arranged in two different loci, srtC1-C2 and srtC3-C4, with a similar genetic organization and are thought to be involved in pilus biosynthesis. Each pair of sortase genes is flanked by LPXTG protein encoding genes, two upstream and one downstream, and a divergently transcribed regulatory gene located upstream from this locus. We demonstrated that strain NEM316 expresses only the srtC3-C4 locus, which encodes three surface proteins (Gbs1474, Gbs1477 and Gbs1478) that polymerize to form appendages resembling pili. Structural and functional analysis of this locus revealed that: (i) the transcriptional activator RogB is required for expression of the srtC3-C4 operon; (ii) Gbs1477, and either SrtC3 or SrtC4 are absolutely required for pilus biogenesis; and (iii) GBS NEM316 pili are composed of three surface proteins, Gbs1477, the bona fide pilin which is the major component, Gbs1474, a minor associated component, and Gbs1478, a pilus-associated adhesin. Surprisingly, pilus-like structures can be formed in the absence of the two minor components, i.e. the putative anchor Gbs1474 or the adhesin Gbs1478. Adherence assays showed that Gbs1478 confers ad...