title: The CSB protein actively wraps DNA.
abstract: The CSB protein is a member of the SWI2/SNF2 family of ATP-dependent chromatin remodeling factors and is essential for transcription-coupled DNA repair. The role of CSB in this DNA repair process is unclear, but the protein was found to remodel nucleosomes and alter DNA double helix conformation upon binding. Elucidating the nature of the change in DNA structure induced by CSB is of great interest for understanding the CSB mechanism of action. We analyzed the CSB.DNA complex by scanning force microscopy and measured a shortening of DNA contour length upon CSB binding in the presence of ATP. This DNA length reduction most likely results from DNA wrapping around the protein. Shorter DNA molecules were observed more frequently in the presence of non-hydrolyzable ATP analogues. These results suggest that DNA wrapping depends on ATP binding, whereas ATP hydrolysis results in unwrapping. We also provide evidence suggesting that CSB binds DNA as a dimer. DNA wrapping and unwrapping allows CSB to actively alter the DNA double helix conformation, which could influence nucleosomes and other protein-DNA interactions.
authors.affiliation: Department of Cell Biology and Genetics and Radiation Oncology, Erasmus Medical Center, P. O. Box 1738, 3000 DR Rotterdam, The Netherlands.
authors.forename: Nancy
authors.initials: N
authors.lastname: Beerens
authors.forename: Jan H J
authors.initials: JH
authors.lastname: Hoeijmakers
authors.forename: Roland
authors.initials: R
authors.lastname: Kanaar
authors.forename: Wim
authors.initials: W
authors.lastname: Vermeulen
authors.forename: Claire
authors.initials: C
authors.lastname: Wyman
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000737:chemistry*; D004265:DNA Helicases / Q000737:chemistry*; D004260:DNA Repair; D045643:DNA Repair Enzymes; D019281:Dimerization; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007091:Image Processing, Computer-Assisted; D015151:Immunoblotting; D047468:Immunoprecipitation; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D000939:Epitopes; D009707:Nucleosomes; D000075223:Poly-ADP-Ribose Binding Proteins; D011506:Proteins; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D004265:DNA Helicases; C078673:ERCC6 protein, human; D045643:DNA Repair Enzymes