FIG. 1.

Schematic diagrams of L. monocytogenes PC-PLC. (a) PC-PLC is translated as a preproprotein. The proform of PC-PLC encompasses the propeptide and the catalytic domain. The pro and active forms of PC-PLC have calculated molecular masses of 30.4 and 27.7 kDa but run as 33- and 28-kDa species on SDS-PAGE. (b) The amino acid sequence of the propeptide is flanked by partial amino acid sequence of the signal peptide and catalytic domain. The Mpl cleavage site is indicated for the wild-type strain. For the PC-PLC S51D S53N mutant, two amino acid residues are mutated, decreasing the efficiency of Mpl cleavage. The PC-PLCΔpro mutant was generated by deletion of the entire propeptide.