[Interaction of RNA polymerase of Escherichia coli with substrate by affinity labeling and NMR with nuclear 31P].

The affinity labeling of E. coli RNA polymerase by periodate oxidized uridine triphosphate was carried out without and with the template (polydeoxynucleotides poly(dA) and poly(dT) ), and under the conditions of poly(dA) and poly(dT) transcription. The extent of RNA polymerase labeling was nearly the same in the presence of poly(dA) and poly(dT) (0.9 and 0.7). However, during the transcription of poly(dA) the extent of RNA polymerase labeling proved to be more than twice as high as that in the case of poly(dT) (0.75 and 0.3). The longitudinal relaxation times (T1) for phosphorus of ATP and dinucleotide pUpU in the complexes of RNA polymerase with the template (poly(dA) and poly(dT) in the presence of MnCl2 were determined. The distance from the phosphorus of enzyme-bound ATP and pUpU and the Mn2+ ion coordinated at the active center on RNA polymerase were calculated using the Solomon - Blombergen formula. According to the results of the affinity labeling of RNA polymerase and the NMR (nuclear magnetic resonance) experiments it can be inferred that the template influences the formation of the working conformation of the enzyme active center, specific with respect to the true substrate, in the stage of RNA elongation.