Genetic studies on the β subunit of Escherichia coli RNA polymerase

Abstract
We have isolated a set of strains that synthesise 331 potential variants of E. coli DNA-dependent RNA polymerase making use of nonsense suppression of amber mutations in the β structural gene; rpoB. Translational mapping, together with the effect of known amino acid substitutions, has allowed us to locate sites on the β polypeptide involved in transcription termination, stringent response and resistance to the antibiotic rifampicin. In general, the C-terminal quarter appears to be less affected by such single amino acid exchanges than the rest of β. These studies permit for the first time structure-function correlates for the β subunit of RNA polymerase.