Interaction between wheat germ RNA polymerase II and adenovirus 2 DNA. Evidence for two types of stable binary complexes

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Abstract
Transcription of adenovirus 2 (Ad 2) DNA by wheat germ RNA polymerase II in vitro satisfies criteria that were used to establish that Escherichia coli or coliphage transcription in vitro is initiated at true promoters. Wheat germ RNA polymerase forms highly stable complexes at specific sites on Ad 2 DNA, with a Kassoc [association constant] of (4-5) .times. 1010 M-1. EM visualization of enzyme bound to Ad 2 DNA reveals the location of 8 strong binding sites, at least 5 of which appear to correspond to promoters that were identified in studies of Ad 2 transcription in vivo. Transcription of Ad 2 DNA from preformed complexes with wheat germ polymerase is capable of escaping the action of rifamycin AF/013 and is relatively resistant to poly(I). These results are consistent with a 2-state model for the interaction of wheat germ RNA polymerase with Ad 2 DNA, indicating that the mechanisms of transcription initiation and promoter-site selection in eukaryotes may be very similar to mechanisms elucidated in prokaryotic systems.