[Selective binding of oligodeoxyribonucleotides with Escherichia coli RNA-polymerase and their effect on...

It was shown previously, that E. coli RNA polymerase selectively binds certain fractions of oligoribonucleotides with the length greater than or equal to 5 nucleotides from the mixtures of random oligonucleotides of definite length. The data presented demonstrate, that E. coli RNA polymerase from the mixtures of random oligodeoxynucleotides of various length selectively binds oligodeoxynucleotides with the length greater than or equal to 9. The activity of the enzyme correlates with its ability to bind oligodeoxynucleotides. The enzyme which has selectively bound oligodeoxynucleotides, manifests sedimentation position characteristic for E. coli RNA polymerase engaged in transcription. The oligodeoxynucleotides with high affinity to the enzyme act as competitive inhibitors of transcription catalyzed by E. coli RNA polymerase. The data suggest that E. coli RNA polymerase bound oligodeoxynucleotides mimic the nucleotide sequences of the promoter responsible for the binding of the enzyme. It was found that selectively bound oligoribo - and oligodeoxynucleotides do not compete for the site on the enzyme. This property of E. coli RNA polymerase is assumed to play a certain role in the regulation of transcription.