Tethering of the large subunits of Escherichia coli RNA polymerase

Abstract

The rpoB and rpoC genes of eubacteria and archaea, coding, respectively, for the β and β'-like subunits of DNA-dependent RNA polymerase, are organized in an operon with rpoB always preceding rpoC. Here, we show that in Escherichia coli the two genes can be fused and that the resulting 2751- amino acid β::β' fusion polypeptide assembles into functional RNA polymerase in vivo and in vitro. The results establish that the C terminus of the β subunit and the N terminus of the β' subunit are in close proximity to each other on the surface of the assembled RNA polymerase during all phases of the transcription cycle and also suggest that RNA polymerase assembly in vivo may occur co-translationally.