Content of RNA polymerase in haploid and merodiploid strains of Escherichia coli

Identification of an amber fragment of the beta subunit of Escherichia coli RNA polymerase: a yardstick for measuring controls on RNA polymerase subunit synthesis

An amber fragment of the beta subunit of Escherichia coli RNA polymerase has been recovered from strains carrying the rpoB12 amber mutation, indicating that the B12 mutation resides in the structural gene for the beta subunit. The fragment is readily assayed and can be used to determine the degree of expression of a single rpoB cistron in strains haploid or diploid for this region. These studies confirm that the bacterial mechanism, which can compensate for reduced translation of the beta message, operates by the co-ordinate induction of rpoB and rpoC. Furthermore, I show that rpo control depends upon cistron(s) located on the F' factor, KLF10, whose product(s) can act negatively in trans on rpoBC expression.

The influence of mutations upon the synthesis of RNA polymerase subunits in Escherichia coli cells

The influence of mutations in structural genes of beta and beta subunits of RNA polymerase upon the synthesis of these subunits in E. coli cells have been investigated. An amber-mutation ts22 in the beta subunit gene decreases the intracellular concentration of this subunit and the rate of its synthesis. At the same time the concentration and the rate of beta subunit synthesis is increased. These suggest the compensatory activation of the RNA polymerase operon that takes place under the conditions of shortage of one of the subunits. Reversions as well as more effective suppression of ts22 amber mutation, achieved by streptomycin addition, substitution of su2 by sul, or by specific mutations, result in a rise of beta and drop of beta subunit concentration and synthesis in ts22 mutant. TsX missense-mutation in the beta subunit gene alters the properties of the enzyme increasing, at the same time, the concentration and the rate of synthesis of both beta and beta subunits, particularly at a nonpermissive temperature. This points to an inversely proportional relationship between the rate of synthesis of RNA polymerase subunits and the total intracellular activity of the enzyme. Extra subunits are rapidly degraded in ts22 and tsX mutants. The whole complex of our data and those of others suggest that the regulation of the synthesis of RNA polymerase subunits is accomplished by interaction of a negative and a positive mechanisms of regulation which include not only activators and repressors but the enzyme itself as well.

Induction of RNA polymerase synthesis in Escherichia coli

Studies on the rate of synthesis of the beta and beta' subunits of RNA polymerase in haploid strains of Escherichia coli K12 containing poorly-suppressed rif degrees am mutations provide conclusive evidence that synthesis of at least these two subunits is regulated.

Regulation of RNA polymerase synthesis in Escherichia coli: a mutant unable to synthesize the enzyme at 43 degrees

We report the isolation of a mutant of E. coli in which the capacity to synthesize RNA polymerase (EC 2.7.7.6) (the beta and beta' subunits) is rapidly lost at 43 degrees. The mutation has no effect on the stability or activity of the polymerase itself. The mutation is recessive and is closely linked to the rif locus (the structural gene for the beta subunit). Using strains carrying the mutation, we have shown that polymerase is present in excess in rapidly growing E. coli cells.