Uncoupling the TFIIH Core and Kinase Modules Leads to High CTD Serine 5 Phosphorylation Throughout Transcription

This multi-subunit complex comprises two modules that are physically linked by the Tfb3 (MAT1 in metazoans). The Core Module carries two DNA-dependent ATPases that unwind DNA, not only for transcription but also nucleotide excision repair.

The Kinase Module phosphorylates the C-terminal domain (CTD) of RNApII subunit Rpb1 to facilitate the transition of initiation complexes to elongation. Yeast Tfb3 can be split into two parts to uncouple the TFIIH modules, and resulting cells are viable but slow-growing. Chromatin immunoprecipitation shows that Core, but not Kinase, is properly recruited to promoters.