Positioning of region 4 of the Escherichia coli RNA polymerase sigma(70) subunit by a transcription activator

A DNA cleavage reagent, specifically tethered to residue 581 of the Escheri chia coli RNA polymerase sigma(70) subunit, has been used to investigate th e location of sigma(70) region 4 in different complexes at the galp(1) prom oter and the effect of the cyclic AMP receptor protein. The positions of DN A cleavage by the reagent are not affected by the cyclic AMP receptor prote in. We conclude that transcription activation at the galp(1) promoter by th e cyclic AMP receptor protein does not involve major conformation changes i n or repositioning of sigma(70) region 4.