MOLECULAR ANALYSIS OF THE LOCUS RESPONSIBLE FOR PRODUCTION OF PLANTARICIN-S, A 2-PEPTIDE BACTERIOCIN PRODUCED BY LACTOBACILLUS-PLANTARUM LPCO10

A 4.5-kb region of chromosomal DNA carrying the locus responsible for the production of plantaricin S, a two-peptide bacteriocin produced by Lactobacillus plantarum LPCO10 (R. Jimenez-Diaz, J. L. Ruiz-Barba, D. P. Cathcart, H. Hole, I. F. Nes, K. H. Sletten, and P. J. Warner, App l. Environ. Microbiol. 61:4459-4463, 1995), has been cloned, and the n ucleotide sequence has been elucidated. Two genes, designated plsA and plsB and encoding peptides alpha and beta, respectively, of plantaric in S, plus an open reading frame (ORF), ORF2, were found to be organiz ed in an operon. Northern blot analysis showed that these genes are co transcribed, giving a ca. 0.7-kb mRNA, whose transcription start point was determined by primer extension. Nucleotide sequences of plsA and plsB revealed that both genes are translated as bacteriocin precursors which include N-terminal leader sequences of the double-glycine type. The role of ORF2 is unknown at the moment, although it might be expec ted to encode an immunity protein of the type described for other bact eriocin operons. In addition, several other potential ORFs have been f ound, including some which may be responsible for the regulation of ba cteriocin production. Two of them, ORF8 and ORF14, show strong homolog y with histidine protein kinase and response regulator genes, respecti vely, which have been found to be involved in the regulation of the pr oduction of other bacteriocins from lactic acid bacteria. A third ORF, ORF5, shows homology with gene agrB from Staphylococcus aureus, which is involved in the mechanism of regulation of the virulence phenotype in this species. Thus, an agr-like regulatory system for the producti on of plantaricin S is postulated.