DNA FLEXIBILITY OF THE UP ELEMENT IS A MAJOR DETERMINANT FOR TRANSCRIPTIONAL ACTIVATION AT THE ESCHERICHIA-COLI ACETATE PROMOTER

The specific interaction of the upstream element-containing promoter o f the Escherichia coli acetate operon with either the RNA polymerase h oloenzyme or its alpha subunit has been analyzed by the base removal m ethod, Our results indicate that: (i) direct and specific base contact s can be detected in the acetate promoter-alpha subunit complex; (ii) base elimination in the upstream element of the acetate promoter enhan ces the binding of RNA polymerase. A similar effect is observed when s tudying the interactions between RNA polymerase and the rrnB ribosomal operon P1 promoter.