Molecular analysis of the lactacin F operon

Abstract

Lactacin F is a nonlantibiotic, heat-stable, peptide bacteriocin produced by LactobaciUus johnsonii VPI11088. Molecular analysis of the lactacin F DNA region characterized a small operon that codes for three open reading frames, designated lafA, laJX, and ORFZ. The peptide encoded by lafA, the lactacin F structural gene, was compared with various peptide bacteriocins from lactic acid bacteria, and similarities were identified in the amino and carboxy termini of the propeptides. Site-directed mutagenesis of the LafA precursor at the two glycine residues in positions-1 and-2 defined an essential motif for processing of mature lactacin F. The involvement of the peptides encoded by laiX and ORFZ in bacteriocin expression was investigated by subcloning various fragments from the lactacin F region into the shuttle vector pGKV210. In addition to lafA, expression of laiX is essential to lactacin F activity. The lactacin F operon resembles the genetic organization of lactococcin M. Although no function has been assigned to ORFZ by genetic analysis, both peptide Z and the lactococcin M immunity protein are predicted to be integral membrane proteins with four putative transmembrane segments. Lactacin F activity, defined by bactericidal action on LactobaciUus delbrueckii, is dependent on the expression of two genes, lafA and lagX.

Cloning and nucleotide sequence of the gene for acidocin 8912, a bacteriocin from Lactobacillus acidophilus TK8912

“…2, the Gly-Gly motif, which is typical among the Class I1 LAB bacteriocin precursors previously described (Klaenhammer 1993), is found at positions -1 and -2, immediately before the processing site. Other characteristic features were also identified : (i) a central region of charged and hydrophilic amino acids ; and (ii) hydrophobic residues at positions -4, -7 and -12 (Fremaux et al 1993). Taken together with its biochemical characteristics (e.g.…”

Functional analysis of the pediocin operon of Pediococcus acidilactici PAC1.0: PedB is the immunity protein and PedD is the precursor processing enzyme

“…Analysis of the pediocin operon 519 the lactacin F structural gene (Fremaux et aL, 1993), and LcnD, which is essential for the production of lactococcins (Stoddard et aL, 1992), are also structurally related to PedC, suggesting that a common mechanism exists for secretion of these small bacteriocin molecules.…”

Nisin-induced expression of pediocin in dairy lactic acid bacteria

“…However, nisinresistant strains of both L. monocytogenes Gravesen et al 2002) and C. botulinum ) have been identified, suggesting a need for additional 'food-grade' bacteriocins. Bacteriocins with potential to serve as food preservatives have been identified in dairy starter LAB, including Streptococcus thermophilus (Villani et al 1995;Ward and Somkuti 1995;Marciset et al 1997;Aktypis et al 1998;Gilbreth and Somkuti 2005;Kabuki et al 2007;Fontaine and Hols 2008) and L. lactis (Holo et al 1991;Fremaux et al 1993;Venema et al 1993;Morgan et al 1995;Delves-Broughton et al 1996;Moll et al 1996;Ferchichi et al 2001;Ghrairi et al 2005;Akcelik et al 2006;Kim et al 2006;Kojic et al 2006;Zendo et al 2006;Rogne et al 2008), and in nonstarter LAB including lactobacilli (Ennahar et al 1996;Miteva et al 1998;Lozo et al 2004;Abo-Amer 2007) and enterococci (Audisio et al 2000;Jin et al 2000;Lund and Edlund 2001;Franz et al 2007). However, the use of enterococci in dairy fermentations is prohibited because of their role as human pathogens and their ability to transfer antibiotic resistance genes.…”