Regulation of subunit synthesis of Escherichia coli RNA polymerase.

lambdacI857s7drif(d)18 phage is a defective, specialized transducing phage carrying the RNA polymerase mutation rif(d), a dominant rifampicin-resistant allele. This phage DNA directs in vitro synthesis of the beta subunit of RNA polymerase in a DNA-dependent protein-synthesizing system. Prophage induction in cells that are lysogenic for this phage increases the rate of beta-subunit synthesis in vivo by at most 2-fold. No increase in subunit synthesis above the haploid level is observed in cells diploid for the beta gene.