Autolysin as a fibronectin receptor on the cell surface of Clostridium perfringens

Objective

Clostridium perfringens causes food poisoning and gas gangrene, a serious wound-associated infection. C. perfringens cells adhere to collagen via fibronectin (Fn). We thought that C. perfringens cells have some kind of Fn receptor. We investigated whether the peptidoglycan hydrolase of C. perfringens, i.e., autolysin (Acp), is implicated in Fn binding to C. perfringens cells.

Methods

This study used recombinant Acp fragments, human Fn and knockout mutants (C. perfringens 13 acp::erm and HN13 ΔfbpC ΔfbpD). Ligand blotting, Western blotting analysis, and complementation tests were performed. The Fn-binding activity of each mutant was evaluated by ELISA.

Results

From an Fn-binding assay using recombinant Acp fragments, Fn was found to bind to the catalytic domain of Acp. In mutant cells lacking Acp, Fn binding was significantly decreased, but was restored by the complementation of the acp gene. There are three known kinds of Fn-binding proteins in C. perfringens: FbpC, FbpD, and glyceraldehyde-3-phosphate dehydrogenase. We found no difference in Fn-binding activity between the mutant cells lacking both FbpC and FbpD (SAK3 cells) and the wild-type cells, indicating that these Fn-binding proteins are not involved in Fn binding to C. perfringens cells.

Conclusions

We found that the Acp is an Fn-binding protein that acts as an Fn receptor on the surface of C. perfringens cells.