RNA polymerase subunit biosynthesis in Bacillus subtilis.

The relative rates of RNA polymerase biosynthesis in Bacillus subtilis has been examined under steady-state growth conditions. The synthesis of RNA polymerase subunits (alpha, beta, beta', omega) has been followed by subunit fractionation of immunoprecipitated [3H]-labelled samples on SDS-polyacrylamide gels. The stoichiometries of alpha:beta:beta':omega subunits have been determined from cultures pulse-labelled during steady-state growth. The results suggest that an unassembled pool of the alpha-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 alpha-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 beta beta'-subunit synthesis was demonstrated.