Gene-regulatory modules in Escherichia coli: nucleoprotein complexes formed by cAMP-CRP and CytR at the nupG promoter.
Repression by CytR depends on the formation of nucleoprotein complexes in which the CytR repressor and the cAMP-CRP activator complex bind co-operatively to the DNA. Transcription initiation from CytR-regulated promoters requires cAMP-CRP; therefore, the cAMP-CRP complex functions both as an activator and as a co-repressor in these promoters. Another interesting aspect of the CytR regulon is that each promoter appears to have individual features. Therefore, structural and functional rules governing the formation of repression and activation complexes in one promoter may not be valid for other promoters of the CytR regulon. Here we show that the Escherichia coli nupG gene contains one CytR- and four CRP-binding sites in the control region. Notably, the architecture of the CytR binding site is different from previously described targets. In addition, the CytR repressor triggers a DNA repositioning of a cAMP-CRP complex in the -35 region upon binding to its operator. Thus, formation of the repression and activation complexes at the nupG promoter involves different subsets of CRP-binding sites. These findings show that the bacterium uses positive and negative regulatory modules to differentially control the expression of CytR- and cAMP-CRP-regulated genes.
Pedersen
H
H
Department of Molecular Biology, Odense University, Denmark.
Dall
J
J
Dandanell
G
G
Valentin-Hansen
P
P
D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D016384:Consensus Sequence; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; C048425:CytR protein, E coli; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009698:Nucleoproteins; C098551:NupG protein, E coli; D012097:Repressor Proteins