title: An antimicrobial peptide is produced by extracellular processing of a protein from Propionibacterium jensenii.
abstract: A protease-activated antimicrobial peptide (PAMP) and its inactive precursor were purified from the culture supernatant of Propionibacterium jensenii LMG 3032 and characterized at the molecular level. PAMP is a 64-amino-acid cationic peptide of 6,383 Da with physicochemical features similar to those of bacteriocins from gram-positive bacteria. This peptide displayed bactericidal activity against several propionibacteria and lactobacilli. DNA sequencing indicated that the PAMP-encoding gene (pamA) is translated as a proprotein of 198 amino acids with an N-terminal signal peptide of 27 amino acids and that PAMP constitutes the C-terminal part of this precursor. The amino acid sequence of pro-PAMP showed no similarity to those of other known proteins. By using activity tests and mass spectrometry, we showed that PAMP was formed upon protease treatment of the precursor protein. The propionibacteria produced the PAMP precursor constitutively during growth up to a level of approximately 4 mg/liter, but the producing bacteria were unable to activate the precursor. The requirement for an external protease represents a novel strategy for generating antimicrobial peptides.
authors.affiliation: Department of Food Science, Agricultural University of Norway, As, Norway.
authors.forename: Therese
authors.initials: T
authors.lastname: Faye
authors.forename: Dag Anders
authors.initials: DA
authors.lastname: Brede
authors.forename: Thor
authors.initials: T
authors.lastname: Langsrud
authors.forename: Ingolf F
authors.initials: IF
authors.lastname: Nes
authors.forename: Helge
authors.initials: H
authors.lastname: Holo
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D001430:Bacteriocins / Q000494:pharmacology; D001483:Base Sequence; D019286:Endopeptidase K / Q000737:chemistry / Q000378:metabolism; D005109:Extracellular Matrix; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011424:Propionibacterium / Q000737:chemistry* / Q000378:metabolism; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017421:Sequence Analysis
chemical_list: D023181:Antimicrobial Cationic Peptides; D001430:Bacteriocins; D011498:Protein Precursors; D019286:Endopeptidase K