Organization and nucleotide sequences of two lactococcal bacteriocin operons

Abstract

Two distinct regions of the Lactococcus lactis subsp. cremoris 9B4 plasmid p9B4-6, each of which specified bacteriocin production as well as immunity, have been sequenced and analyzed by deletion and frameshift mutation analyses. On a 1.8-kb ScaI-ClaI fragment specifying low antagonistic activity, three open reading frames (ORFs) were present, which were organized in an operon. The first two ORFs, containing 69 and 77 codons, respectively, were involved in bacteriocin activity, whereas the third ORF, containing 154 codons, was essential for immunity. Primer extension analysis indicated the presence of a promoter upstream of the ORFs. Two ORFs were present on a 1.3-kb ScaI-HindIII fragment specifying high antagonistic activity. The first ORF, containing 75 codons, specified bacteriocin activity. The second ORF, containing 98 codons, specified immunity. The nucleotide sequences of both fragments upstream of the first ORFs as well as the first 20 bp of

Genetics of bacteriocins produced by lactic acid bacteria

“…However, investigation of conjugal transfer systems in lactococci revealed that the Bac + and Imm + determinants were commonly encoded by self-transmissible elements [33,49,50]. Genetic characterization of conjugal 'Bac' determinants on pNP2 (133 kb; [51]) and p9B4-6 (60 kb; [33]) identified three distinct bacteriocins, designated lactococcins A, B, and M [21,[51][52][53][54][55]. Genetic analyses of the bacteriocin operons, coupled with biochemical analysis of lactococcin A and its mechanism of action, have uncovered an exciting model system for study of the expression, regulation, processing, and action of lactococcins [39].…”

“…Two bacteriocins were identified because each Imm + did not cross-protect against the other bacteriocin. DNA sequence analysis [21] revealed two distinct bacteriocin operons ( Fig. 1).…”

“…(IIa) Listeria-active peptides with a consensus sequence in the N-terminal of-Tyr-Gly-Asn-G[y-Val-Xaa-Cys-; characterized by pediocin PA-1, sakacin A, sakacin P, leucocin A, curvacin A (lib) Poration complexes consisting of two proteinaceous peptides for activity; lactococcin G, lactococcin M, lactacin F [15,20,21].…”

Progress and potential in the biotechnology of lactic acid bacteria

“…In this regard it is notable that a group of small heat stable peptides has been defined. This includes bacteriocins produced by diverse lactic acid bacteria and sequence analysis is available for lactocins A, B and M from L. lactis [10,[121][122][123] lactocin F from Lactobacillus acidophilus [11,124], leucocin A UAL-187 from Leuconostoc gelidium [125] and pediocin PA-1 from Pediococcus acidilactici [9].…”

“…One significant trend since the last symposium is the application of protein engineering techniques in lactic acid bacteria, notable examples being the lactococcal proteinase [4], the lactose repressor gene of Lactococcus lactis [5] and the lantibiotic nisin [6,7]. Bacteriocins in general have been characterized in considerable detail, including examples of additional lantibiotics such as lactocin S from Lactobacillus sake [8] and the emergence of a group of related 'small heat stable bacteriocins' which are produced by several different species of lactic acid bacteria [9][10][11]. Interest in bacteriocins is to some extent fuelled by their potcntial as novcl biopreservativcs and several show promise in this regard.…”