title: Interplay between human high mobility group protein 1 and replication protein A on psoralen-cross-linked DNA.
abstract: Human high mobility group box (HMGB) 1 and -2 proteins are highly conserved and abundant chromosomal proteins that regulate chromatin structure and DNA metabolism. HMGB proteins bind preferentially to DNA that is bent or underwound and to DNA damaged by agents such as cisplatin, UVC radiation, and benzo[a]pyrenediol epoxide (BPDE). Binding of HMGB1 to DNA adducts is thought to inhibit nucleotide excision repair (NER), leading to cell death, but the biological roles of these proteins remain obscure. We have used psoralen-modified triplex-forming oligonucleotides (TFOs) to direct a psoralen-DNA interstrand cross-link (ICL) to a specific site to determine the effect of HMGB proteins on recognition of these lesions. Our results reveal that human HMGB1 (but not HMGB2) binds with high affinity and specificity to psoralen ICLs, and interacts with the essential NER protein, replication protein A (RPA), at these lesions. RPA, shown previously to bind tightly to these lesions, also binds in the presence of HMGB1, without displacing HMGB1. A discrete ternary complex is formed, containing HMGB1, RPA, and psoralen-damaged DNA. Thus, HMGB1 has the ability to recognize ICLs, can cooperate with RPA in doing so, and likely modulates their repair by the NER machinery. The abundance of HMGB1 suggests that it may play an important role in determining the sensitivity of cells to DNA damage under physiological, experimental, and therapeutic conditions.
authors.affiliation: Department of Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1-C, Smithville, Texas 78957, USA.
authors.forename: Madhava C
authors.initials: MC
authors.lastname: Reddy
authors.forename: Jesper
authors.initials: J
authors.lastname: Christensen
authors.forename: Karen M
authors.initials: KM
authors.lastname: Vasquez
mesh_terms: D001483:Base Sequence; D001667:Binding, Competitive; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024243:HMGB1 Protein / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000378:metabolism; D009841:Oligonucleotides / Q000378:metabolism*; D011485:Protein Binding; D051716:Replication Protein A; D014307:Trioxsalen / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D004268:DNA-Binding Proteins; D024243:HMGB1 Protein; D009692:Nucleic Acid Heteroduplexes; D009841:Oligonucleotides; C497167:RPA1 protein, human; D051716:Replication Protein A; C051802:triplex DNA; D004247:DNA; D014307:Trioxsalen