Identification of an Operon and Inducing Peptide Involved in the Production of Lactacin B by Lactobacillus Acidophilus

J Appl Microbiol. 2007 Nov;103(5):1766-78. doi: 10.1111/j.1365-2672.2007.03417.x.

Abstract

Aim: To determine if a 9.5-kb region on the Lactobacillus acidophilus NCFM genome, encoded the genetic determinants for regulation and production of lactacin B, a class II bacteriocin.

Methods: Transcriptional analysis was used to identify a 9.5-kb polycistronic region suspected of encoding the lab operon. The 12 putative open reading frames (LBA1803-LBA1791) were organized into three clusters: a production and regulation cluster encoding a putative two-component signal transduction system; an export cluster encoding a putative ABC transporter and a final cluster composed of three unknown proteins. Seven genes were typical of bacteriocins, encoding small, cationic peptides, each with an N-terminal double-glycine leader motif. Inactivation of a predicted ABC transporter completely abolished bacteriocin activity. When cloned and expressed together, LBA1803-LBA1800 resulted in markedly higher levels of lactacin B activity. The four peptides were chemically synthesized but exhibited no bacteriocin activity, alone or in combination. Only LBA1800 induced lactacin B production in broth cultures.

Conclusions: Lactacin B production is encoded within the 9.5-kb lab operon of 12 genes that are transcribed in a single transcript. LBA1800 is an inducing peptide of bacteriocin production.

Significance and impact of the study: A three-component regulatory system common to class II bacteriocins regulates the production of this bacteriocin by Lact. acidophilus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • Amino Acid Sequence
  • Bacteriocins / analysis
  • Bacteriocins / biosynthesis*
  • Bacteriological Techniques
  • Base Sequence
  • Cloning, Molecular
  • Gene Expression Regulation, Bacterial*
  • Intracellular Signaling Peptides and Proteins
  • Lactobacillus acidophilus / genetics*
  • Lactobacillus acidophilus / metabolism*
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Operon*
  • Peptides / genetics
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Transcription, Genetic

Substances

  • ATP-Binding Cassette Transporters
  • Bacteriocins
  • Intracellular Signaling Peptides and Proteins
  • Peptides
  • inducing factor, Lactobacillus
  • lactocin