title: Isolation and characterization of two human transcription factor IIH (TFIIH)-related complexes: ERCC2/CAK and TFIIH.
abstract: Transcription factor IIH (TFIIH) is a multisubunit protein complex essential for both the initiation of RNA polymerase class II (pol II)-catalyzed transcription and nucleotide excision repair of DNA. Recent studies have shown that TFIIH copurifies with the cyclin-dependent kinase (cdk)-activating kinase complex (CAK) that includes cdk7, cyclin H, and p36/MAT1. Here we report the isolation of two TFIIH-related complexes: TFIIH* and ERCC2/CAK. TFIIH* consists of a subset of the TFIIH complex proteins including ERCC3 (XPB), p62, p44, p41, and p34 but is devoid of detectable levels of ERCC2 (XPD) and CAK. ERCC2/CAK was isolated as a complex that exhibits CAK activity that cosediments with the three CAK components (cdk7, cyclin H, and p36/MAT1) as well as the ERCC2 (XPD) protein. TFIIH* can support pol II-catalyzed transcription in vitro with lower efficiency compared with TFIIH. This TFIIH*-dependent transcription reaction was stimulated by ERCC2/CAK. The ERCC2/CAK and TFIIH* complexes are each active in DNA repair as shown by their ability to complement extracts prepared from ERCC2 (XPD)- and ERCC3 (XPB)-deficient cells, respectively, in supporting the excision of DNA containing a cholesterol lesion. These data suggest that TFIIH* and ERCC2/CAK interact to form the TFIIH holoenzyme capable of efficiently assembling the pol II transcription initiation complex and directly participating in excision repair reactions.
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Reardon
authors.forename: H
authors.initials: H
authors.lastname: Ge
authors.forename: E
authors.initials: E
authors.lastname: Gibbs
authors.forename: A
authors.initials: A
authors.lastname: Sancar
authors.forename: J
authors.initials: J
authors.lastname: Hurwitz
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Pan
mesh_terms: D000818:Animals; D016466:CHO Cells; D002852:Chromatography, Ion Exchange; D006224:Cricetinae; D018844:Cyclin-Dependent Kinases / Q000302:isolation & purification* / Q000378:metabolism; D004265:DNA Helicases; D004260:DNA Repair; D004268:DNA-Binding Proteins; D006801:Humans; D011506:Proteins / Q000302:isolation & purification* / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000302:isolation & purification* / Q000378:metabolism; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic; D051759:Xeroderma Pigmentosum Group D Protein
chemical_list: D004268:DNA-Binding Proteins; D011506:Proteins; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D018844:Cyclin-Dependent Kinases; D012319:RNA Polymerase II; D004265:DNA Helicases; D051759:Xeroderma Pigmentosum Group D Protein; C497292:ERCC2 protein, human