Clostridium difficile sortase recognizes a (S/P)PXTG sequence motif and can accommodate diaminopimelic acid as a substrate for transpeptidation

Abstract

Covalent attachment of surface proteins to the cell wall of Gram-positive bacteria requires a sortase-mediated transpeptidation reaction. In almost all Gram-positive bacteria, the housekeeping sortase, sortase A, recognizes the canonical recognition sequence LPXTG (X=any amino acid). The human pathogen Clostridium difficile carries a single putative sortase gene (cd2718) but neither transpeptidation activity nor specificity of CD2718 has been investigated. We produced recombinant CD2718 and examined its transpeptidation activity in vitro using synthetic peptides and MALDI-ToF(-ToF) MS analysis. We demonstrate that CD2718 has sortase activity with specificity for a (S/P)PXTG motif and can accommodate diaminopimelic acid as a substrate for transpeptidation.

Keywords: Adhesion; Diaminopimelic acid; Mass spectrometry; Peptidoglycan; Transpeptidation; Virulence.