Prevalence of the Genes Encoding Propionicin T1 andProtease-Activated Antimicrobial Peptide and Their Expressionin ClassicalPropionibacteria

Abstract

The purpose of this study was to investigate the frequency of production of the bacteriocin propionicin T1 and the protease-activated antimicrobial peptide (PAMP) and their corresponding genes in 64 isolates of classical propionibacteria. This study revealed that these genes are widespread in Propionibacterium jensenii and Propionibacterium thoenii but absent from the remaining species of classical propionibacteria that were studied. The pro-PAMP-encoding gene (pamA) was found in 63% of the P. jensenii strains and 61% of the P. thoenii strains, and all of these strains displayed PAMP activity. The propionicin T1-encoding gene (pctA) was present in 89% of the P. thoenii strains and 54% of the P. jensenii strains. All P. thoenii strains containing the pctA gene exhibited antimicrobial activity corresponding to propionicin T1 activity, whereas only 38% of the pctA-containing P. jensenii strains displayed this activity. Sequencing of the pctA genes revealed the existence of two allelic variants that differed in a single nucleotide in six strains of P. jensenii; in these strains the glycine at position 55 of propionicin T1 was replaced by an aspartate residue (A variant). No strains harboring the A variant showed any antimicrobial activity against propionicin T1-sensitive bacteria. An open reading frame (orf2) located immediately downstream from the pctA gene was absent in three strains containing the G variant of propionicin T1. Two of these strains showed low antimicrobial activity, while the third strain showed no antimicrobial activity at all. The protein encoded by orf2 showed strong homology to ABC transporters, and it has been proposed previously that this protein is involved in the producer immunity against propionicin T1. The limited antimicrobial activity exhibited by the strains lacking orf2 further suggests that this putative ABC transporter plays an important role in propionicin T1 activity.Antimicrobial peptides are important components of the innate defenses in all species of organisms (8, 21). Antimicrobial peptides produced by bacteria are generally referred to as bacteriocins, which include the posttranslationally modified lantibiotics. Bacteriocins and bacteriocin-like peptides are usually ribosomally synthesized, even though it has been shown that some antimicrobial peptides from bacteria are formed by degradation of larger proteins (5,24,25).The classical propionibacteria are gram-positive bacteria with a long history of safe use in dairy fermentations, especially in the production of Swiss-type cheeses, where they are responsible for the formation of flavor and the characteristic eyes. It has also been proposed that propionibacteria may function as probiotic organisms for humans and animals (2, 17).A variety of antimicrobial compounds are produced by propionibacteria; these compounds include propionic acid, acetic acid, and diacetyl in addition to the antimicrobial peptides (9). Although a number of antimicrobial activities of propionibacteria have been reported, only three antimicrobial peptide...

Molecular and Genetic Characterization of Propionicin F, a Bacteriocin fromPropionibacterium freudenreichii

“…It is possible that the mature form of PAMP is produced via proteolytic cleavage of the proprotein by a hitherto undisclosed protease (11). The production of propionicin T1 and pro-PAMP is prevalent in P. jensenii and P. thoenii strains but has not been identified as occurring in P. freudenreichii (12). In fact, no bacteriocin has been purified from P. freudenreichii, although the antimicrobial potential of this organism has frequently been demonstrated (1,19,31).…”

Heterologous Production of Antimicrobial Peptides in Propionibacterium freudenreichii

“…A recent survey on the prevalence of the pctA gene revealed that 13 of 24 P. jensenii strains contained this gene. However, only five strains produced antimicrobial activity corresponding to propionicin T1 (8). Intriguingly, six of the propionicin T1-negative P. jensenii strains contained a G3A transition mutation in the pctA gene, resulting in the amino acid substitution G 55 D in the mature bacteriocin (8).…”

“…However, only five strains produced antimicrobial activity corresponding to propionicin T1 (8). Intriguingly, six of the propionicin T1-negative P. jensenii strains contained a G3A transition mutation in the pctA gene, resulting in the amino acid substitution G 55 D in the mature bacteriocin (8). In order to investigate the biological activity of this propionicin T1 variant, the mutated gene (pctA-A) was cloned under the control of the P 4E promoter in the pAMT1 vector.…”

“…The production of pro-PAMP is prevalent among strains of P. jensenii and P. thoenii (8). It has been suggested that the secretion of an inactive probacteriocin, whose activation relies on proteases in the environment, might represent a novel strategy for production of antimicrobial peptides and producer self-protection (7).…”

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

“…Most strains of P. jensenii and P. thoenii produce and export the pro-PAMP protein, which is has no antimicrobial activity (31). However, the antimicrobial activity is produced extracellularly via proteolytic processing of the N-terminal part of the proprotein of the protease-activated antimicrobial peptide (PAMP).…”