Characterization by molecular cloning and sequencing of the gene encoding an aminopeptidase from Listeria monocytogenes

The pepC gene of Listeria monocytogenes encodes aminopeptidase C that is pr edicted to share 72% amino acid sequence similarity and 53% sequence identi ty with the cysteine aminopeptidase PepC from Lactococcus lactis. The gene product also shows strong similarity to aminopeptidase C from Streptococcus thermophilus and Lactobacillus helveticus, and to a cysteine proteinase/bl eomycin hydrolase from Saccharomyces cerevisiae. The enzyme from L. monocyt ogenes displayed broad N-terminal hydrolytic activity, with a similar subst rate specificity to its lactic acid bacterial counterpart. The inhibition s pectrum shows a great deal of similarity with enzymes from the family of la ctic acid bacteria. In addition, one of the clones studied contained DNA se quences that could encode a regulatory protein of the deoR helix-turn-helix DNA binding protein family. The organization of the locus, designated pep, is presented along with the characterization of the gene products of the p ep locus.