Interaction site of Escherichia coli cyclic AMP receptor protein on DNA of galactose operon promoters.
Cyclic AMP (cAMP) and its receptor protein (CRP) have a dual role in the regulation of the two promoters that control the galactose (gal) operon of Escherichia coli. One promoter, P1, requires cAMP-CRP for activity; the other, P2, is inhibited by these factors. We have examined the interactions site of cAMP-CRP on gal DNA by using two types of protection experiments, involving DNase digestion and methylation by dimethyl sulfate. Our results indicate that cAMP-CRP binds to gal DNA in a segment located between 50 and 24 base pairs preceding the P1 start point for transcription. Although the location of the cAMP-CRP interaction site is clearly different in gal and lac DNA, comparison of the DNA sequences suggests a similar recognition sequence. The location of the cAMP . CRP-binding site in gal further suggests that protein-protein interactions between RNA polymerase and cAMP . CRP play an important role in transcription initiation at the gal and possibly other cAMP-dependent promoters.
D001483:Base Sequence; D000242:Cyclic AMP / Q000378:metabolism*; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000378:metabolism*; D003851:Deoxyribonucleases; D004926:Escherichia coli / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism*; D009876:Operon; D011953:Receptors, Cyclic AMP / Q000378:metabolism*
D004269:DNA, Bacterial; D011953:Receptors, Cyclic AMP; D000242:Cyclic AMP; D003851:Deoxyribonucleases; D004262:DNA Restriction Enzymes; D005690:Galactose