[Effect of mutation changes in RNA-polymerase and transcription termination factor rho on expression of various operons in E. coli]

Abstract

Six mutations, impairing DNA polymerase of E. coli in combination with the wild type gene for rho factor or ts-mutation rho 15 have been studied in relation to the expression of seven operons having different types of regulation. The expression of genes for glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase is shown to be constitutive and resistant to mutationally altered RNA polymerase and rho factor. The expression of genes for adenine phosphoribosyltransferase and of deo operon is regulated by rho dependent attenuators with attenuation being lifted incomplete medium. Mutation rho 15 decreases the level of enzymes of thr and lac operons independent of mRNA levels of these operons. Mutation rho 15 effect on posttranscriptional level is modified by mutations damaging RNA polymerase. The data obtained suppose RNA polymerase to affect all stages of realization of genetic information, beginning with promoter recognition and RNA synthesis and including the protein synthesis on mRNA.