A common ATP requirement for open complex formation and transcription at promoters containing initiator or TATA elements.

The involvement of ATP during transcription initiation from three basic types of RNA polymerase II promoters was investigated. Hydrolysis of the beta-gamma bond of ATP was found to be required for transcription at TATA, initiator, and initiator + TATA promoters. For all three promoters, ATP is required to melt the transcription start site region during formation of a functional open transcription complex. The use of ATP to open the DNA strands occurs rapidly. The resulting open complex is transient, since the start site re-closes rapidly upon initiation. The requirements for efficient open complex formation were similar to those for transcription in that both upstream elements and a basal element, either TATA or initiator, were necessary. The results further suggest that TATA-dependent and initiator-dependent preinitiation complex assembly pathways converge, prior to a step in which the strands are rapidly opened in the presence of ATP, to form analogous open complexes.