Publication in PNAS: Double-stranded DNA translocase activity of TFIIH and the mechanism of RNAP Polymerase II Open Complex formation.

The essential transcription initiation factor TFIIH translocates along double-stranded DNA. The Ssl2 subunit, previously thought to act as a helicase to convert dsDNA into ssDNA actually walks along dsDNA without unwinding. This explains structural results showing that Ssl2 does not contact the site of initial DNA unwinding during initiation and suggests an indirect mechanism of DNA opening at eukaryotic promoters.