DNA repair helicase: a component of BTF2 (TFIIH) basic transcription factor.

The human BTF2 basic transcription factor (also called TFIIH), which is similar to the delta factor in rat and factor b in yeast, is required for class II gene transcription. A strand displacement assay was used to show that highly purified preparation of BTF2 had an adenosine triphosphate-dependent DNA helicase activity, in addition to the previously characterized carboxyl-terminal domain kinase activity. Amino acid sequence analysis of the tryptic digest generated from the 89-kilodalton subunit of BTF2 indicated that this polypeptide corresponded to the ERCC-3 gene product, a presumed helicase implicated in the human DNA excision repair disorders xeroderma pigmentosum and Cockayne's syndrome. These findings suggest that transcription and nucleotide excision repair may share common factors and hence may be considered to be functionally related.