title: Increased and imbalanced dNTP pools symmetrically promote both leading and lagging strand replication infidelity.
abstract: The fidelity of DNA replication requires an appropriate balance of dNTPs, yet the nascent leading and lagging strands of the nuclear genome are primarily synthesized by replicases that differ in subunit composition, protein partnerships and biochemical properties, including fidelity. These facts pose the question of whether imbalanced dNTP pools differentially influence leading and lagging strand replication fidelity. Here we test this possibility by examining strand-specific replication infidelity driven by a mutation in yeast ribonucleotide reductase, rnr1-Y285A, that leads to elevated dTTP and dCTP concentrations. The results for the CAN1 mutational reporter gene present in opposite orientations in the genome reveal that the rates, and surprisingly even the sequence contexts, of replication errors are remarkably similar for leading and lagging strand synthesis. Moreover, while many mismatches driven by the dNTP pool imbalance are efficiently corrected by mismatch repair, others are repaired less efficiently, especially those in sequence contexts suggesting reduced proofreading due to increased mismatch extension driven by the high dTTP and dCTP concentrations. Thus the two DNA strands of the nuclear genome are at similar risk of mutations resulting from this dNTP pool imbalance, and this risk is not completely suppressed even when both major replication error correction mechanisms are genetically intact.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umea University, Umea, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umea University, Umea, Sweden.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Buckland
authors.affiliation: Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina, United States of America.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Watt
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umea University, Umea, Sweden.
authors.forename: Balasubramanyam
authors.initials: B
authors.lastname: Chittoor
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umea University, Umea, Sweden.
authors.forename: Anna Karin
authors.initials: AK
authors.lastname: Nilsson
authors.affiliation: Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina, United States of America.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kunkel
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umea University, Umea, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umea University, Umea, Sweden.
authors.forename: Andrei
authors.initials: A
authors.lastname: Chabes
mesh_terms: D020137:Base Pair Mismatch; D001483:Base Sequence; D053843:DNA Mismatch Repair; D004261:DNA Replication / Q000235:genetics*; D003838:Deoxyadenine Nucleotides / Q000378:metabolism*; D003845:Deoxycytosine Nucleotides / Q000378:metabolism*; D003848:Deoxyguanine Nucleotides / Q000378:metabolism*; D042822:Genomic Instability; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000502:physiology*; D059645:Mutation Rate; D030781:Organisms, Genetically Modified; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013942:Thymine Nucleotides / Q000378:metabolism*
chemical_list: D003838:Deoxyadenine Nucleotides; D003845:Deoxycytosine Nucleotides; D003848:Deoxyguanine Nucleotides; D013942:Thymine Nucleotides; C024107:2'-deoxycytidine 5'-triphosphate; C029603:deoxyguanosine triphosphate; C026600:2'-deoxyadenosine triphosphate; C024157:thymidine 5'-triphosphate