title: Analyses of the interaction between the origin binding domain from simian virus 40 T antigen and single-stranded DNA provide insights into DNA unwinding and initiation of DNA replication.
abstract: DNA helicases are essential for DNA metabolism; however, at the molecular level little is known about how they assemble or function. Therefore, as a model for a eukaryotic helicase, we are analyzing T antigen (T-ag) the helicase encoded by simian virus 40. In this study, nuclear magnetic resonance (NMR) methods were used to investigate the transit of single-stranded DNA (ssDNA) through the T-ag origin-binding domain (T-ag OBD). When the residues that interact with ssDNA are viewed in terms of the structure of a hexamer of the T-ag OBD, comprised of residues 131 to 260, they indicate that ssDNA passes over one face of the T-ag OBD and then transits through a gap in the open ring structure. The NMR-based conclusions are supported by an analysis of previously described mutations that disrupt critical steps during the initiation of DNA replication. These and related observations are discussed in terms of the threading of DNA through T-ag hexamers and the initiation of viral DNA replication.
authors.affiliation: Department of Biochemistry A703, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA.
authors.forename: Danielle K
authors.initials: DK
authors.lastname: Reese
authors.forename: Gretchen
authors.initials: G
authors.lastname: Meinke
authors.forename: Anuradha
authors.initials: A
authors.lastname: Kumar
authors.forename: Stephanie
authors.initials: S
authors.lastname: Moine
authors.forename: Kathleen
authors.initials: K
authors.lastname: Chen
authors.forename: James L
authors.initials: JL
authors.lastname: Sudmeier
authors.forename: William
authors.initials: W
authors.lastname: Bachovchin
authors.forename: Andrew
authors.initials: A
authors.lastname: Bohm
authors.forename: Peter A
authors.initials: PA
authors.lastname: Bullock
mesh_terms: D000595:Amino Acid Sequence; D000957:Antigens, Viral, Tumor / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D017434:Protein Structure, Tertiary; D018741:Replication Origin / Q000235:genetics; D016415:Sequence Alignment; D013539:Simian virus 40
chemical_list: D000957:Antigens, Viral, Tumor; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004265:DNA Helicases