Genetic studies on the β subunit of Escherichia coli RNA polymerase

Abstract
RNA polymerase was isolated from two suppressed rpoB amber strains exhibiting relaxed control over RNA synthesis in vivo. In vitro transcription analysis of these mutant holoenzymes carrying defined substitutions at known sites in the β subunit clearly shows that single amino acid changes in β render RNA polymerase resistant to ppGpp. This unambiguously demonstrates that RNA polymerase is indeed the target for ppGpp.