Activation control of pur gene expression in Lactococcus lactis: proposal for a consensus activator binding sequence based on deletion analysis and site-directed mutagenesis of purC and purD promoter regions.
A comparison of the purC and purD upstream regions from Lactococcus lactis revealed the presence of a conserved ACCGAACAAT decanucleotide sequence located precisely between -79 and -70 nucleotides upstream from the transcriptional start sites. Both promoters have well-defined -10 regions but lack sequences resembling -35 regions for sigma70 promoters. Fusion studies indicated the importance of the conserved sequence in purine-mediated regulation. Adjacent to the conserved sequence in purC is a second and similar region required for high-level expression of the gene. A consensus PurBox sequence (AWWWCCGAACWWT) could be proposed for the three regions. By site-directed mutagenesis we found that mutation of the central G in the PurBox sequence to C resulted in low levels of transcription and the loss of purine-mediated regulation at the purC and purD promoters. Deletion analysis also showed that the nucleotides before the central CCGAAC core in the PurBox sequence are important. All results support the idea that purC and purD transcription is regulated by a transcriptional activator binding to the PurBox sequence.
Department of Microbiology, Technical University of Denmark, DK2800 Lyngby, Denmark. mk@im.dtu.dk
M
M
Kilstrup
S G
SG
Jessing
S B
SB
Wichmand-Jørgensen
M
M
Madsen
D
D
Nilsson
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D019731:Carbon-Nitrogen Ligases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D016384:Consensus Sequence; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010453:Peptide Synthases; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry; D017384:Sequence Deletion; D015534:Trans-Activators; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D019731:Carbon-Nitrogen Ligases; D010453:Peptide Synthases; C083513:PurC protein, Bacteria; C022387:phosphoribosylamine-glycine ligase