Altered synthesis and stability of RNA polymerase holoenzyme subunits in mutants of Escherichia coli with mutations in the beta or beta' subunit genes.

Bacteria with specific temperature sensitive lethal mutations in the gene for the beta' subunit of RNA polymerase synthesize both the beta and beta' subunits at a several fold higher rate at 42 degrees C than wild-type cells relative to total protein. Synthesis of the alpha and sigma subunits proceeds at essentially the wild-type rates under these conditions. In contrast, a mutant with a temperature sensitive lethal mutation in the beta subunit gene synthesizes beta and beta' at 42 degrees C at slightly lower rates than wild-type, while alpha and sigma synthesis is not significantly altered. In all of the mutants at 42 degrees C, newly synthesized alpha subunits are stable, while the beta, beta' and sigma subunits are rapidly degraded. The apparent uncoupling of betabeta' and alpha subunit synthesis seen in the beta' mutants at 42 degrees C might suggest that the synthesis of these subunits is at least in part controlled by different mechanisms.