Dual role of TFIIH in DNA excision repair and in transcription by RNA polymerase II

Abstract

The RNA polymerase II general transcription factor TFIIH is composed of several polypeptides. The observation that the largest subunit of TFIIH is the excision-repair protein XPB/ERCC3 (ref. 1), a helicase implicated in the human DNA-repair disorders xeroderma pigmentosum (XP) and Cockayne's syndrome, suggests a functional link between transcription and DNA repair. To understand the connection between these two cellular processes, we have extensively purified and functionally analysed TFIIH. We find that TFIIH has a dual role, being required for basal transcription of class II genes and for participation in DNA-excision repair. TFIIH is shown to complement three different cell extracts deficient in excision repair: XPB/ERCC3, XPC and XPD/ERCC2. The complementation of XPB and XPD is a consequence of ERCC3 and ERCC2 being integral subunits of TFIIH, whereas complementation of XPC is due to an association of this polypeptide with TFIIH. We found that the general transcription factor IIE negatively modulates the helicase activity of TFIIH through a direct interaction between TFIIE and the ERCC3 subunit of TFIIH.

The Human Immunodeficiency Virus Transactivator Tat Interacts with the RNA Polymerase II Holoenzyme

“…Although TFIIH is part of the holoenzyme, phosphorylation of the CTD by TFIIH occurs only following the assembly of the initiation complex onto DNA (12,13). Our model simplifies the loading of Tat onto the LTR and might also explain the ability of Tat to activate transcription via DNA (45).…”

“…Previously, we also purified the holoenzyme by conventional chromatography (36). Nuclear extracts were fractionated on a phosphocellulose column followed by DEAE-Sephacel and DEAE-5PW columns (13,16). Fractions containing pol II were identified by Western blotting and loaded onto an S-Sepharose column (36).…”

Retrovirus-mediated gene transfer corrects DNA repair defect of xeroderma pigmentosum cells of complementation groups A, B and C

“…10 So far, most of the relevant human genes, proteins play a dual role in both NER and transcripsuch as XPA, XPB, XPC, XPD, XPF and XPG, have been tion. [20][21][22] cloned and mapped to different specific chromosomal The mean age of XP patients at the time of diagnosis locations. A further source of NER defective mutants is a is 3 years while the mean age of onset of first skin cancer set of 11 complementation groups of UV-sensitive rodent is 8 years.…”

Interethnic variability of ERCC2 polymorphisms

“…5 Damaged DNA fragments containing between 24 and 32 nucleotides may be excised through incisions made in NER. 4,6,7 Polymorphisms in ERCC2 may have a profound effect on DNA repair, and can result in xeroderma pigmentosum, trichothiodystrophy, or Cockayne's syndrome. 1,[8][9][10] Several studies have also associated polymorphisms in ERCC2 with response to platinum therapy, lung cancer risk, and DNA repair capacity.…”