Non-Essential Sequences in the β Subunit of E.Coli RNA Polymerase

Abstract

We have initiated a study on the β subunit of RNA polymerase with the aim of defining regions necessary for enzyme function. Using nonsense suppression of amber mutations which inactivate expression of rpoB, we have identified sites involved in mediating rifampicin resistance, the stringent response and transcription termination (1). The ability to correlate the effect of known amino acid substitutions with the site of the mutation in rpoB has allowed us to create a preliminary structure-function map for the β polypeptide. Interestingly, the majority of the substitutions that alter RNA polymerase function are located in the second and third quarters of the gene (1).