Protein-protein interactions in gene regulation: the cAMP-CRP complex sets the specificity of a second DNA-binding protein, the CytR repressor.
Maximal repression by the CytR protein depends on the formation of nucleoprotein complexes in which CytR interacts with DNA and with cAMP-cAMP receptor protein (CRP). Here we demonstrate that CytR regulates transcription from deoP2 promoters in which the entire CytR recognition sequence has been eliminated. Furthermore, CytR proteins deleted for the DNA-binding domain repress deoP2 in vivo and interact with deoP2 in vitro in a strictly cAMP-CRP-dependent fashion. These experiments show that the site of action of CytR can be specified by protein-protein interactions to cAMP-CRP, whereas CytR-DNA interactions may primarily serve to stabilize the nucleo-protein complex. This type of specificity mechanism may represent a general concept in the recruitment of DNA-binding proteins in combinatorial regulatory systems.
Søgaard-Andersen
L
L
Department of Molecular Biology, Odense University, Denmark.
Valentin-Hansen
P
P
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D000242:Cyclic AMP / Q000378:metabolism*; D004794:Enzyme Repression; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009875:Operator Regions, Genetic / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011953:Receptors, Cyclic AMP / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; C048425:CytR protein, E coli; D029968:Escherichia coli Proteins; D011953:Receptors, Cyclic AMP; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D000242:Cyclic AMP