Resumen de Rapid Switching of TFIIH between RNA Polymerase I and II Transcription and DNA Repair In Vivo

A. L. Nigg, H. Heath, D. Hoogstraten

• The transcription/repair factor TFIIH operates as a DNA helix opener in RNA polymerase II (RNAP2) transcription and nucleotide excision repair. To study TFIIH in vivo, we generated cell lines expressing functional GFP-tagged TFIIH. TFIIH was homogeneously distributed throughout the nucleus with nucleolar accumulations. We provide in vivo evidence for involvement of TFIIH in RNA polymerase I (RNAP1) transcription. Photobleaching revealed that TFIIH moves freely and gets engaged in RNAP1 and RNAP2 transcription for ∼25 and ∼6 s, respectively. TFIIH readily switches between transcription and repair sites (where it is immobilized for ∼4 min) without large-scale alterations in composition. Our findings support a model of diffusion and random collision of individual components that permits a quick and versatile response to changing conditions.