title: The structure and duplex context of DNA interstrand crosslinks affects the activity of DNA polymerase η.
abstract: Several important anti-tumor agents form DNA interstrand crosslinks (ICLs), but their clinical efficiency is counteracted by multiple complex DNA repair pathways. All of these pathways require unhooking of the ICL from one strand of a DNA duplex by nucleases, followed by bypass of the unhooked ICL by translesion synthesis (TLS) polymerases. The structures of the unhooked ICLs remain unknown, yet the position of incisions and processing of the unhooked ICLs significantly influence the efficiency and fidelity of bypass by TLS polymerases. We have synthesized a panel of model unhooked nitrogen mustard ICLs to systematically investigate how the state of an unhooked ICL affects pol η activity. We find that duplex distortion induced by a crosslink plays a crucial role in translesion synthesis, and length of the duplex surrounding an unhooked ICL critically affects polymerase efficiency. We report the synthesis of a putative ICL repair intermediate that mimics the complete processing of an unhooked ICL to a single crosslinked nucleotide, and find that it provides only a minimal obstacle for DNA polymerases. Our results raise the possibility that, depending on the structure and extent of processing of an ICL, its bypass may not absolutely require TLS polymerases.
authors.affiliation: Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA.
authors.forename: Upasana
authors.initials: U
authors.lastname: Roy
authors.affiliation: Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA.
authors.forename: Shivam
authors.initials: S
authors.lastname: Mukherjee
authors.affiliation: Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-3400, USA.
authors.forename: Anjali
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA.
authors.forename: Ekaterina G
authors.initials: EG
authors.lastname: Frank
authors.affiliation: Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-3400, USA orlando.scharer@stonybrook.edu.
authors.forename: Orlando D
authors.initials: OD
authors.lastname: Schärer
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D004249:DNA Damage; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D013329:Structure-Activity Relationship
chemical_list: D003432:Cross-Linking Reagents; D004247:DNA; D004259:DNA-Directed DNA Polymerase