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DNA‐protein recognition: demonstration of three genetically separated operator elements that are required for repression of the Escherichia coli deoCABD promoters by the DeoR repressor.
Author(s) -
ValentinHansen P.,
Albrechtsen B.,
Løve Larsen J.E.
Publication year - 1986
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1986.tb04458.x
Subject(s) - repressor , promoter , psychological repression , biology , escherichia coli , lac repressor , dna , lac operon , operator (biology) , genetics , gene , operon , microbiology and biotechnology , gene expression
The sequences required for full repression of the Escherichia coli deoP1 and P2 promoters by the deoR repressor (DeoR) have been analyzed in vivo. Using recombinant techniques, we have constructed a set of deo‐lacZ fusions which contain different parts of the sequences involved in the regulation of deo expression on low copy number fusion vectors. Since these vectors are present in only one copy per chromosome at temperatures below 37 degrees C, this vector system allows very accurate studies of gene control signals. Our results show that three DeoR operator sites exist in the deoP1‐P2 regulatory region. Two of these loci overlap the initiation sites for deoP1 (O1) and deoP2 (O2) transcription located 599 bp apart, whereas the third site (OE) is present approximately 270 bp upstream of P1. DeoR repression of both P1 and P2 transcription is weak on promoter fragments which only contain one operator site (O1 or O2). Enhanced repression by deoR is observed on promoter fragments containing two operator sites. However, all three sites are needed for full repression. These findings are discussed with respect to upstream and downstream control regions of eukaryotic genes.