Cyclic AMP receptor protein (CRP) regulates the expression of more then 100 genes inEscherichia coli. It is known that the allosteric activation of CRP by cAMP involves a long-distance signal transmission from the N-ter-minal cAMP-binding domain to the C-terminal domain of CRP responsible for the interactions with specific sequences of DNA. In this report we have used a CRP mutant containing a single Trp13 located in the N-terminal domain of the protein.