HYBRID BORDETELLA-PERTUSSIS ESCHERICHIA COLI RNA-POLYMERASES - SELECTIVITY OF PROMOTER ACTIVATION

We constructed hybrid Bordetella pertussis-Escherichia coil RNA polyme rases and compared productive interactions between transcription activ ators and cognate RNA polymerase subunits in an in vitro transcription system. Virulence-associated genes of B. pertussis, in the presence o f their activator BvgA, are transcribed by all variants of hybrid RNA polymerases, whereas transcription at the E. coli lac promoter regulat ed by the cyclic AMP-catabolite gene activator protein has an absolute requirement for the E. coli alpha subunit. This suggests that activat or contact sites involve a high degree of selectivity.