[Selective binding of oligoribonucleotides by T7 phage induced RNA-polymerase]

It was shown previously that E. coli RNA-polymerase being incubated with the random oligonucleotide mixtures of definite length binds certain oligoribonucleotides with the length greater than or equal to 5 nucleotides. The data presented demonstrate that T7 phage induced RNA-polymerase (T7 RNA-polymerase) also binds selectively oligoribonucleotides beginning from pentaribonucleotides. From the random mixtures of penta-, hexa-, hepta-, octa-, nona- and decaribonucleotides the hepta- and octaribonucleotides are bound most efficiently. The T7 RNA-polymerase bound oligoribonucleotides can be completely extracted from the random mixture by the addition of the redundant enzyme amounts. As far as E. coli RNA-polymerase and T7 RNA-polymerase do not compete for the oligoribonucleotides the conclusion is made that they bind different oligoribonucleotides. The addition of the T7 DNA to the previously formed T7 RNA-polymerase--heptaribonucleotide complex competitively displace the heptaribonucleotides from the complex; the competitive effect of T4 DNA is very low. The data suggest that the oligoribonucleotides which are selectively bound by the RNA-polymerase are attached to the enzyme site responsible for the interaction with the promotor.