The wild-type nucleotide sequence of the rpoBC-attenuator region of Escherichia coli DNA and its implications for the nature of the rifd18 mutation

To investigate the possibility that the unusual dominant rifampicin-resistance characteristic of the rifd18 allele of E. coli rpoB is due to a secondary, regulatory mutation, we have determined the nucleotide sequence of a 1.1 Kbp wild-type DNA fragment, including the transcriptional attenuator and translational start-site of rpoB. We have also re-investigated the previously published sequences of this region in lambda rifd18 and lambda rifd47 DNA. Our results indicate that all three sequences are identical, and reveal some errors in the published data. We discuss the basis of dominance of rifd18.