[Role of RNA polymerase in ensuring fidelity in copying the template during transcription in E. coli].

The heterogeneity of cell size of E. coli WU-36-10-11-12 and its four RNA-polymerase (rif-r) mutants with pleiotropic effect -- rpoB401, rpoB402, rpoB403 and rpoB409 was investigated for the purposeful choice of E. coli mutant with an altered fidelity of transcription. The stability of the phenotype of E. coli strains was shown to depend on the structural state of RNA polymerase. In vitro RNA-polymerase of the morphologically most unstable mutant rpoB402 incorporates non-complementary GMP or CMP on the poly [d(AT).d(AT)] template more frequently than the enzyme from the wild-type strain. The data obtained suggest that the beta-subunit of RNA-polymerase determines the fidelity of transcription and the selection of complementary nucleotides.