Our results obtained by monitoring DNA bubble size with magnetic tweezers constrain possible mechanisms of DNA unwinding and reveal that DNA unwinding occurs in two separate steps. An initial step catalyzed by TFIIH leads to the melting of 6 bp while subsequent initial transcription by RNAP II expands the bubble to 15 bp.
Our single-molecule work on the mechanism of transcription initiation in Eukaryotes is published in NSMB.
