title: Human XPC-hHR23B interacts with XPA-RPA in the recognition of triplex-directed psoralen DNA interstrand crosslinks.
abstract: DNA interstrand crosslinks (ICLs) represent a severe form of damage that blocks DNA metabolic processes and can lead to cell death or carcinogenesis. The repair of DNA ICLs in mammals is not well characterized. We have reported previously that a key protein complex of nucleotide excision repair (NER), XPA-RPA, recognizes DNA ICLs. We now report the use of triplex technology to direct a site-specific psoralen ICL to a target DNA substrate to determine whether the human global genome NER damage recognition complex, XPC-hHR23B, recognizes this lesion. Our results demonstrate that XPC-hHR23B recognizes psoralen ICLs, which have a structure fundamentally different from other lesions that XPC-hHR23B is known to bind, with high affinity and specificity. XPC-hHR23B and XPA-RPA protein complexes were also observed to bind psoralen ICLs simultaneously, demonstrating not only that psoralen ICLs are recognized by XPC-hHR23B alone, but also that XPA-RPA may interact cooperatively with XPC-hHR23B on damaged DNA, forming a multimeric complex. Since XPC-hHR23B and XPA-RPA participate in the recognition and verification of DNA damage, these results support the hypothesis that interplay between components of the global genome repair sub-pathway of NER is critical for the recognition of psoralen DNA ICLs in the mammalian genome.
authors.affiliation: Department of Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Science Park-Research Division Smithville, TX 78957, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Thoma
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Wakasugi
authors.forename: Jesper
authors.initials: J
authors.lastname: Christensen
authors.forename: Madhava C
authors.initials: MC
authors.lastname: Reddy
authors.forename: Karen M
authors.initials: KM
authors.lastname: Vasquez
mesh_terms: D003432:Cross-Linking Reagents / Q000633:toxicity*; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005363:Ficusin / Q000633:toxicity*; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D051716:Replication Protein A; D051760:Xeroderma Pigmentosum Group A Protein
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; C513287:RAD23B protein, human; C497167:RPA1 protein, human; D051716:Replication Protein A; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; C051802:triplex DNA; C086985:RAD23A protein, human; C086984:XPC protein, human; D004247:DNA; D045643:DNA Repair Enzymes; D005363:Ficusin