Possible hyperattenuation of transcription in the Escherichia coli hisG gene cloned in Bacillus subtilis.

The expression of the E. coli hisG gene in B. subtilis cells does not occur in spite of the faithful replication of the relevant DNA fragment cloned in this host by means of a plasmid vector, pHV14 , capable of replication in both B. subtilis and E. coli. Analysis of the RNA transcribed in vitro and in vivo by the B. subtilis RNA polymerase on the cloned hisG sequence indicates that in B. subtilis cells the physiological his operon promoter is not recognized. Transcription is initiated at many sites, some of which are located upstream of and some are located downstream of the his operon promoter. These "adventitious" promoters give rise to convergent transcription products which stop at, or in the vicinity of, the his operon attenuator sequence.