RNA polymerase subunit biosynthesis in Bacillus subtilis

Summary

The relative rates of RNA polymerase biosynthesis in Bacillus subtilis has been examined under steady-state growth conditions. The synthesis of RNA polymerase subunits (α, β, β′, σ) has been followed by subunit fractionation of immunoprecipitated [³H]-labelled samples on SDS-polyacrylamide gels. The stoichiometries of α:β:β′:σ subunits have been determined from cultures pulse-labelled during steady-state growth. The results suggest that an unassembled pool of the α-subunit exists from which the holoenzyme is formed.

Upon shift-up from acetate to glycerol containing medium, a rapid rise in the differential rate of core enzyme synthesis was observed, while the rate of synthesis of the α-subunit was not stimulated. During shift-down, a concomitant reduction in the rate of synthesis of all subunits occurred for the first 20 min after the shift; thereafter, a rate of synthesis characteristic of the new growth rate was established.

As cultures enter sporulation, an immediate reduction in the rate of β β′-subunit synthesis was demonstrated.