Two acid-inducible promoters from Lactococcus lactis require the cis-acting ACiD-box and the transcription regulator RcfB.
We previously characterized three Lactococcus lactis promoters, P170, P1 and P3, which are induced by low pH. Here, we identified a novel 14 bp regulatory DNA region centred at around -41.5 and composed of three tetranucleotide sequences, boxes A, C and D. Boxes A and C contribute to P1 activity, whereas box D and the position of boxes ACD (renamed ACiD-box) are essential to P1 activity and acid response. We also identified a trans -acting protein, RcfB, which is involved in P170 and P1 basal activity and is essential for their pH induction. The regulator belongs to the Crp-Fnr family of transcription regulators. Overexpression of rcfB resulted in increased beta-galactosidase activities and lantibiotic lacticin 481 production from P170- and P1-controlled genes, respectively, in acid condition. RcfB is thus probably activated when cells encounter an acid environment. rcfB is co-transcribed with genes encoding an universal stress-like protein and a multidrug transporter. RcfB plays a role in acid adaptation, as the survival rate of an rcfB mutant after a lethal acid challenge was 130-fold lower than that of the wild-type strain, when the bacteria were first grown in acidic medium. The groESL promoter includes a sequence resembling an ACiD-box and the chaperone GroEL production is partly RcfB dependent in acid condition. Our results suggest that the ACiD-box could be the DNA target site of RcfB.
Madsen
Søren M
SM
Bioneer A/S, Kogle Allé 2, DK-2970 Hørsholm, Denmark. sma@bioneer.dk
Hindré
Thomas
T
Le Pennec
Jean-Paul
JP
Israelsen
Hans
H
Dufour
Alain
A
D000143:Acids / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001430:Bacteriocins / Q000096:biosynthesis; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D020868:Gene Silencing; D005809:Genes, Regulator; D013294:Lactococcus lactis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D000143:Acids; D001426:Bacterial Proteins; D001430:Bacteriocins; D002352:Carrier Proteins; D018834:Chaperonin 60; D004251:DNA Transposable Elements; D014157:Transcription Factors; C082508:lacticin 481