Selection by T7 RNA polymerase of T7 DNA as the template for RNA synthesis

Abstract

Retention of [ 3H]thymidine-labeled T7 DNA on a membrane filter by T7 RNA polymerase was investigated in the presence or absence of three ribonucleoside triphosphates (ATP, GTP and UTP, or ATP, GTP and CTP). In the absence of three NTPs, the retention was prevented markedly by preincubation of T7 polymerase with T4 DNA or λ DNA, but the polymerase tended to bind to T7 DNA added afterward when three NTPs were present. Formation of T7 polymerase-DNA-NTPs complex was observed only in the experiment using T7 DNA. The data indicate that the selection by T7 polymerase of true template DNA is performed only in the presence of NTPs.