title: Mechanism of repair of 5'-topoisomerase II-DNA adducts by mammalian tyrosyl-DNA phosphodiesterase 2.
abstract: The topoisomerase II (topo II) DNA incision-and-ligation cycle can be poisoned (for example following treatment with cancer chemotherapeutics) to generate cytotoxic DNA double-strand breaks (DSBs) with topo II covalently conjugated to DNA. Tyrosyl-DNA phosphodiesterase 2 (Tdp2) protects genomic integrity by reversing 5'-phosphotyrosyl-linked topo II-DNA adducts. Here, X-ray structures of mouse Tdp2-DNA complexes reveal that Tdp2 β-2-helix-β DNA damage-binding 'grasp', helical 'cap' and DNA lesion-binding elements fuse to form an elongated protein-DNA conjugate substrate-interaction groove. The Tdp2 DNA-binding surface is highly tailored for engagement of 5'-adducted single-stranded DNA ends and restricts nonspecific endonucleolytic or exonucleolytic processing. Structural, mutational and functional analyses support a single-metal ion catalytic mechanism for the exonuclease-endonuclease-phosphatase (EEP) nuclease superfamily and establish a molecular framework for targeted small-molecule blockade of Tdp2-mediated resistance to anticancer topoisomerase drugs.
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, North Carolina, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Schellenberg
authors.forename: C Denise
authors.initials: CD
authors.lastname: Appel
authors.forename: Sanjay
authors.initials: S
authors.lastname: Adhikari
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Robertson
authors.forename: Dale A
authors.initials: DA
authors.lastname: Ramsden
authors.forename: R Scott
authors.initials: RS
authors.lastname: Williams
mesh_terms: D000818:Animals; D002384:Catalysis; D018360:Crystallography, X-Ray; D018736:DNA Adducts; D004260:DNA Repair; D004250:DNA Topoisomerases, Type II / Q000737:chemistry*; D051379:Mice; D008958:Models, Molecular; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry*
chemical_list: D018736:DNA Adducts; D010727:Phosphoric Diester Hydrolases; C122147:tyrosyl-DNA phosphodiesterase; D004250:DNA Topoisomerases, Type II