Identification, characterization, and expression of a second, bicistronic, operon involved in the production of lactocin S in Lactobacillus sakei L45.
Through the analysis of spontaneous insertion mutants of Lactobacillus sakei L45, a second operon involved in lactocin S production was identified and characterized. The new, bicistronic unit, termed lasXY, is situated immediately upstream of the previously characterized nine-open reading frame (ORF) lactocin S operon (lasA-W) and is transcribed in the opposite direction. The proximal of the two newly identified genes, lasX, specifies a 285-residue protein that is similar to a group of proteins with reported gene regulation functions in gram-positive bacteria. It was demonstrated that the lasX mutants have a strongly reduced level of lasA and lasA-W mRNA, thus indicating the likely cause of the Bac(-) phenotype of these mutants. The second ORF in the operon, lasY, specifies a 300-residue ABC transporter homolog, the function of which is currently obscure. Transcription initiation mapping of the lasXY operon demonstrates that the two lactocin S promoters overlap such that both transcripts initiate within the -35 region of the oppositely oriented promoter. This organization of promoters is unique among this group of regulons and may constitute a modulatory site in the proposed LasX-dependent expression of lasA and downstream genes.
Skaugen
Morten
M
Laboratory of Microbial Gene Technology, Agricultural University of Norway, P.O. Box 5051, N-1432 As-NLH, Norway. morten.skaugen@ikb.nlh.no
Andersen
Elizabeth L
EL
Christie
Vigdis H
VH
Nes
Ingolf F
IF
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001430:Bacteriocins; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D007778:Lactobacillus / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics* / Q000502:physiology*; D010455:Peptides; D012333:RNA, Messenger; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001430:Bacteriocins; D010455:Peptides; D012333:RNA, Messenger; C103925:lactocin S