Structural and biochemical characterization of Clostridium perfringens pili protein B collagen‐binding domains

Abstract

Sortase‐mediated pili are flexible rod proteins composed of major and minor/tip pilins, playing important roles in the initial adhesion of bacterial cells to host tissues. The pilus shaft is formed by covalent polymerization of major pilins, and the minor/tip pilin is covalently attached to the tip of the shaft involved in adhesion to the host cell. The Gram‐positive bacterium Clostridium perfringens has a major pilin, and a minor/tip pilin (CppB) with the collagen‐binding motif. Here, we report X‐ray structures of CppB collagen‐binding domains, collagen‐binding assays and mutagenesis analysis, demonstrating that CppB collagen‐binding domains adopt an L‐shaped structure in open form, and that a small β‐sheet unique to CppB provides a scaffold for a favourable binding site for collagen peptide.