The XBP-Bax1 helicase-nuclease complex unwinds and cleaves DNA: implications for eukaryal and archaeal nucleotide excision repair.

ABSTRACT: XPB helicase is an integral part of transcription factor TFIIH, required for both transcription initiation and nucleotide excision repair (NER). Along with the XPD helicase, XPB plays a crucial but only partly understood role in defining and extending the DNA repair bubble around lesions in NER. Archaea encode clear homologues of XPB and XPD, and structural studies of these proteins have yielded key insights relevant to the eukaryal system. Here we show that archaeal XPB functions with a structure-specific nuclease, Bax1, as a helicase-nuclease machine that unwinds and cleaves model NER substrates. DNA bubbles are extended by XPB and cleaved by Bax1 at a position equivalent to that cut by the XPG nuclease in eukaryal NER. The helicase activity of archaeal XPB is dependent on the conserved

SUBMITTER: Rouillon C 

PROVIDER: S-EPMC2856306 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature