Abstract
Mutations in XPB, an essential subunit of the transcription/repair factor TFIIH, lead to nucleotide excision repair (NER) defects and xeroderma pigmentosum (XP). The role of XPB in NER and the molecular mechanisms resulting in XP are poorly understood. Here, we show that the p52 subunit of TFIIH interacts with XPB and stimulates its ATPase activity. A mutation found among XP-B patients (F99S) weakens this interaction and the resulting ATPase stimulation, thereby explaining the defect in the damaged DNA opening. We next found that mutations in the helicase motifs III (T469A) and VI (Q638A) that inhibit XPB helicase activity preserve the NER function of TFIIH. Our results suggest a mechanism in which the helicase activity of XPB is not used for the opening and repair of damaged DNA, which is instead only driven by its ATPase activity, in combination with the helicase activity of XPD.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Amino Acid Substitution
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DNA Damage
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DNA Helicases / chemistry
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DNA Helicases / genetics
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DNA Helicases / metabolism*
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DNA Repair*
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Humans
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In Vitro Techniques
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Molecular Sequence Data
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Multiprotein Complexes
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Mutagenesis, Site-Directed
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Protein Subunits
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Transcription Factor TFIIH / chemistry
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Transcription Factor TFIIH / metabolism*
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Xeroderma Pigmentosum Group D Protein / chemistry
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Xeroderma Pigmentosum Group D Protein / genetics
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Xeroderma Pigmentosum Group D Protein / metabolism*
Substances
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DNA-Binding Proteins
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Multiprotein Complexes
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Protein Subunits
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Recombinant Proteins
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XPBC-ERCC-3 protein
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Transcription Factor TFIIH
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DNA Helicases
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Xeroderma Pigmentosum Group D Protein
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ERCC2 protein, human