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 ϳ4 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.Antimicrobial peptides are produced by all kinds of organisms, from bacteria to mammals. In higher organisms these compounds are produced as an innate host defense mechanism to protect against pathogenic attack, whereas microorganisms presumably use these compounds as weapons in the competition for limited resources. A large number of antimicrobial peptides have been isolated from amphibians (35), fish (2, 22), insects (32), mammals (13), plants (1), and different microorganisms (12). Antimicrobial proteins and peptides from bacteria include toxins like diphtheria and cholera toxins (24, 25), bacteriolytic enzymes like lysostaphin (30) and hemolysins (8), and bacteriocins and bacteriocin-like peptides (10, 12). Numerous bacteriocins have been characterized from grampositive bacteria, and some of them show a relatively broad spectrum of inhibition. Antimicrobial peptides produced by food-grade organisms such as lactic acid bacteria and propionibacteria have received special interest due to their potential applications in food preservation (33).The classical propionibacteria have a long history of use in dairy fermentations, in particular the production of Swiss-type cheeses. A few antimicrobial peptides from these bacteria have been described so far (7,9,14,15,17,21,29), and only two bacteriocins have been characterized at the molecular level (7,17).Bacteria use a number of different mechanisms to regulate and produce active peptides and proteins. Most conventional bacteriocins are produced as precursor peptides, which are modified posttranslationally inside the cell or at the cell exterior during export to generate their biologically active forms (12). However, it has been shown that antimicrobial peptides from both bacteria (27, 28) and higher organisms (23, 31) can be produced from the degradation of larger proteins.In this work we describe a novel antimicrobial pe...

Characterization of Bacillus Probiotics Available for Human Use

“…The remaining probiotic strains had little or no effect on the growth of indicator strains under these experimental conditions. Importantly, we observed in parallel studies that B. clausii strain Enterogermina, which had no effect in the previous screening, became active if the plate area surrounding its growth spot was treated with proteinase K before addition of the indicator strains (9). Of the three indicator strains tested, the inhibitory effect was seen with L. innocua but not with B. megaterium 899 or C. perfringens.…”

Dairy Propionibacteria: Less Conventional Probiotics to Improve the Human and Animal Health

“…Propionibacteria also produce other peptides and organic acids (2-pyrrolidone-5-carboxylic acid, 3-phenyllactic acid, hydroxyphenyl lactic acid 3-phenyllactic acid) with antiviral, antiyeasts and antifungal activities [91][92][93].…”

ThefsrQuorum-Sensing System and Cognate Gelatinase Orchestrate the Expression and Processing of Proprotein EF_1097 into the Mature Antimicrobial Peptide Enterocin O16

“…A similar phenomenon has been described in Propionibacterium jensenii (30). Most strains of P. jensenii and P. thoenii produce and export the pro-PAMP protein, which is has no antimicrobial activity (31).…”

“…Subsequently, the secreted pro-PAMP protein comprising 198 amino acids was purified from culture supernatant not subjected to protease treatment. Moreover, formation of PAMP upon protease treatment of purified pro-PAMP was demonstrated (30). However, no host-encoded proteinase that enables efficient production of PAMP in vivo has hitherto been identified.…”