title: Organization and expression of a gene cluster involved in the biosynthesis of the lantibiotic lactocin S.
abstract: Some 8.8 kb of the Lactobacillus sake plasmid pCIM1 was sequenced, revealing eight tightly clustered open reading frames (ORFs) downstream from lasA, which encodes pre-lactocin S. Transcription analyses demonstrated that the genes are expressed as an operon, with transcription initiating upstream of lasA and terminating immediately 3' to the ninth ORF x lasA is also represented by two small RNAs (RNAI and RNAII) which differ in size by approximately 90 nucleotides, and primer extension experiments demonstrated a corresponding difference in the 5' termini. A palindromie sequence constitutes the 3' terminus of both RNAI and RNAII, and we propose that this sequence has a dual regulatory function in controlling the expression of las operon, acting both as a barrier to 3'-5' exonuclease degradation of the lasA-specific transcript(s), and as a "leaky" transcriptional terminator which limits the expression of down-stream genes. Three of the genes in the las operon have identifiable counterparts in other lantibiotic systems: lasM is likely to be involved in prepeptide modification, lasT, which encodes an ATP-dependent transport protein, is probably involved in the secretion of lactocin S, while lasP specifies a subtilisin-type serine protease which may be the lactocin S leader peptidase. Insertional mutation of either lasT or lasM by the resident transposable element IS1163 abolishes lactocin S production. The remaining five ORFs in the las operon are apparently unique, and their significance with respect to the lactocin S phenotype is presently not known.
authors.affiliation: Laboratory of Microbial Gene Technology, Agricultural University of Norway, As.
authors.forename: M
authors.initials: M
authors.lastname: Skaugen
authors.forename: C I
authors.initials: CI
authors.lastname: Abildgaard
authors.forename: I F
authors.initials: IF
authors.lastname: Nes
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001430:Bacteriocins; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D015870:Gene Expression; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D009876:Operon; D010455:Peptides; D014158:Transcription, Genetic
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D004269:DNA, Bacterial; D010455:Peptides; C103925:lactocin S