Dynamics of TFIIH and Spt4/5 during the transition from transcription initiation to elongation.

TFIIH dissociates categorically before Spt4/5 arrives on RNA polymerase II in yeast, leaving a clear interval when neither factor is present.

• Why it matters: The initiation-to-elongation transition requires timely factor exchange, but overlapping factor occupancy raises uncertainty about whether Spt4/5 actively displaces TFIIH.
• What they did: Labeled yeast nuclear extracts were combined with single-molecule fluorescence microscopy to track TFIIH and Spt4/5 dynamics in real time during the transition.
• The result: Spt4/5 binding is not required to dissociate TFIIH from RNA polymerase II, implying dissociation occurs independently of Spt4/5 arrival.