AN ARCANE ROLE OF DNA IN TRANSCRIPTION ACTIVATION

The mechanism by which the cAMP receptor protein (CRP) activates trans cription has been investigated using the lac promoter of Escherichia c oil. For transcription activation, an interaction between DNA-bound CR P and RNA polymerase is not sufficient. CRP must bind to a site in the same DNA and close to the promoter. CRP action requires an intact spa cer DNA to provide a rigid support in building a CRP-RNA polymerase pr otein bridge or to allow a conformational change in the DNA to be tran smitted to the lac promoter using the protein bridge as a structural s upport.