Interactions between the Escherichia coli cyclic AMP receptor protein and RNA polymerase at class II promoters.

The effects of a number of mutations in crp have been measured at different cyclic AMP receptor protein (CRP)-dependent Class II promoters, where the CRP-binding site is centred around 41 1/2 base pairs upstream from the transcription start point. The amino acid substitutions HL159 and TA158 result in reduced CRP-dependent activation, but the reduction varies from one Class II promoter to another. Deletions in the C-terminus of the RNA polymerase alpha subunit suppress the effects of HL159 and TA158. The role of the C-terminus of alpha at these promoters is assessed. Other changes at E58, K52 and E96 affect CRP activity specifically at Class II promoters and their role is discussed.