title: DNA structural elements required for ERCC1-XPF endonuclease activity.
abstract: The heterodimeric complex ERCC1-XPF is a structure-specific endonuclease responsible for the 5' incision during mammalian nucleotide excision repair (NER). Additionally, ERCC1-XPF is thought to function in the repair of interstrand DNA cross-links and, by analogy to the homologous Rad1-Rad10 complex in Saccharomyces cerevisiae, in recombination between direct repeated DNA sequences. To gain insight into the role of ERCC1-XPF in such recombinational processes and in the NER reaction, we studied in detail the DNA structural elements required for ERCC1-XPF endonucleolytic activity. Recombinant ERCC1-XPF, purified from insect cells, was found to cleave stem-loop substrates at the DNA junction in the absence of other proteins like replication protein A, showing that the structure-specific endonuclease activity is intrinsic to the complex. Cleavage depended on the presence of divalent cations and was optimal in low Mn2+ concentrations (0.2 mM). A minimum of 4-8 unpaired nucleotides was required for incisions by ERCC1-XPF. Splayed arm and flap substrates were also cut by ERCC1-XPF, resulting in the removal of 3' protruding single-stranded arms. All incisions occurred in one strand of duplex DNA at the 5' side of a junction with single-stranded DNA. The exact cleavage position varied from 2 to 8 nucleotides away from the junction. One single-stranded arm, protruding either in the 3' or 5' direction, was necessary and sufficient for correct positioning of incisions by ERCC1-XPF. Our data specify the engagement of ERCC1-XPF in NER and allow a more direct search for its specific role in recombination.
authors.affiliation: Department of Cell Biology and Genetics, Medical Genetics Centre, Erasmus University, P. O. Box 1738, 3000 DR Rotterdam, The Netherlands.
authors.forename: W L
authors.initials: WL
authors.lastname: de Laat
authors.forename: E
authors.initials: E
authors.lastname: Appeldoorn
authors.forename: N G
authors.initials: NG
authors.lastname: Jaspers
authors.forename: J H
authors.initials: JH
authors.lastname: Hoeijmakers
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D003432:Cross-Linking Reagents; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D004789:Enzyme Activation; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C095888:xeroderma pigmentosum group F protein; D004247:DNA; C071447:ERCC1 protein, human; D004720:Endonucleases