Identification of the nucleotide sequence recognized by the cAMP-CRP dependent CytR repressor protein in the deoP2 promoter in E. coli.
In E. coli repression of transcription initiation by the CytR protein relies on CytR-DNA interactions as well as on interactions between CytR and the cAMP-CRP activator complex. To identify the nucleotide sequence recognized by CytR, mutants of the deoP2 promoter with a reduced regulatory response to CytR have been isolated. Five single bp mutation derivatives of deoP2 with a 2-5-fold decrease in CytR regulation have been characterized. In vitro, the only effect of the mutations was a decrease in the binding affinity of CytR, and a clear correlation was observed between the reduction in CytR regulation in vivo and the reduction in CytR binding in vitro. The mutations all reside in a sequence element that contains an imperfect direct as well as an imperfect inverted repeat. As the active form of CytR, most likely, is an oligomer with two-fold rotational symmetry, CytR probably interacts with the inverted repeat. Degenerate versions of the inverted repeat are present in all CytR binding sites characterized so far, however, the distance between the half-sites varies.
Rasmussen
P B
PB
Department of Molecular Biology, Odense University, Denmark.
Søgaard-Andersen
L
L
Valentin-Hansen
P
P
D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins / Q000502:physiology*; D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011953:Receptors, Cyclic AMP / Q000502:physiology*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000502:physiology*; D012977:Sodium Nitrite
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; C048425:CytR protein, E coli; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D011953:Receptors, Cyclic AMP; D012097:Repressor Proteins; D012977:Sodium Nitrite