INTERACTIONS BETWEEN THE ESCHERICHIA-COLI CYCLIC-AMP RECEPTOR PROTEINAND RNA-POLYMERASE AT CLASS-II PROMOTERS

The effects of a number of mutations in crp have been measured at diff erent cyclic AMP receptor protein (CRP)-dependent Class II promoters, where the CRP-binding site is centred around 41 1/2 base pairs upstrea m from the transcription start point. The amino acid substitutions HL1 59 and TA158 result in reduced CRP-dependent activation, but the reduc tion varies from one Class II promoter to another. Deletions in the C- terminus of the RNA polymerase alpha subunit suppress the effects of H L159 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 sp ecifically at Class II promoters and their role is discussed.