Clostridium perfringens is an often-harmful intestinal bacterium that causes various diseases ranging from food poisoning to life-threatening fulminant disease. Potential treatments include phage-derived endolysins, a promising family of alternative antimicrobial agents. We surveyed the genome of the C. perfringens st13 strain and identified an endolysin gene, psa, in the phage remnant region. Psa has an N-terminal catalytic domain that is homologous to the amidase_2 domain, and a C-terminal domain of unknown function. psa and gene derivatives encoding various Psa subdomains were cloned and expressed in Escherichia coli as N-terminal histidine-tagged proteins. Purified His-tagged full-length Psa protein (Psa-his) showed C. perfringens-specific lytic activity in turbidity reduction assays. In addition, we demonstrated that the uncharacterized C-terminal domain has cell wall-binding activity. Furthermore, cell wall-binding measurements showed that Psa binding was highly specific to C. perfringens. These results indicated that Psa is an amidase endolysin that specifically lyses C. perfringens; the enzyme’s specificity is highly dependent on the binding of the C-terminal domain. Moreover, Psa was shown to have a synergistic effect with another C. perfringens-specific endolysin, Psm, which is a muramidase that cleaves peptidoglycan at a site distinct from that targeted by Psa. The combination of Psa and Psm may be effective in the treatment and prevention of C. perfringens infections.
One Repeat of the Cell Wall Binding Domain Is Sufficient for Anchoring the Lactobacillus acidophilus Surface Layer Protein
