Regulation of Transcription by cAMP and cAMP receptor protein in Escherichia coli

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The transcription of Escherichia coli cya gene by cAMP and its receptor protein(CRP) has been studied. The transcription of cya gene was shown to be negatively regulated by cAMP-CRP in vitro. The cAMP-CRP complex binds specifically to the cya promoter region to inhibit the transcription. The negative regulation of the cya transcription was also shown in vivo by S1 nuclease and RNA dot blot assays. The cya-lac gene fusion studies gave another evidence for the cya regulation by cAMP- CRP.The whole genome of E.coli was digested by a restriction enzyme and the resulting DNA fragments were randomly cloned into a promoter selection cloning vector. Among about 100 clones, 5 have been shown to contain promoters that can be activated by cAMP. Additionally one promoter, which transcription is represses by cAMP, was also isolated. The DNA sequences of these promoters have been determined. Most of promoters sequenced turned out to corresponds to unknown genes.