Non-coordinate synthesis of RNA polymerase ββ′ subunits in a temperature-sensitive β′-subunit mutant of Escherichia coli

Summary

On exposure to high temperature of a temperature-sensitive RNA polymerase β′ subunit (rpoC92) mutant of Escherichia coli, selective reduction was observed in the rate of synthesis of a group of proteins including RNA polymerase β′ subunit. The finding that the synthesis of β′ subunit but not β subunit was specifically repressed in this mutant grown at non-permissive temperature indicates that the functionally intact RNA polymerase is required for the synthesis of ββ′ subunits be coordinated. In addition, the assembly of newly synthesized RNA polymerase subunits was inefficient in this mutant at the steps where altered β′ subunit was involved, and the unassembled enzyme subunits were rapidly and preferentially degraded. During recovery to non-restricted growth, the synthesis of both β and β′ subunits was transiently enhanced in parallel leading to recovery of the intracellular concentration of functional RNA polymerase.