Basis of Miscoding of the DNA Adduct N2,3-Ethenoguanine by Human Y-family DNA Polymerases.

(2012) J Biological Chem 287: 35516-35526

• PubMed: 22910910 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1074/jbc.M112.403253
• Primary Citation of Related Structures:  
  4FS1,4FS2


• PubMed Abstract: 
  

  N(2),3-Ethenoguanine (N(2),3-εG) is one of the exocyclic DNA adducts produced by endogenous processes (e.g. lipid peroxidation) and exposure to bioactivated vinyl monomers such as vinyl chloride, which is a known human carcinogen. Existing studies exploring the miscoding potential of this lesion are quite indirect because of the lability of the glycosidic bond. We utilized a 2'-fluoro isostere approach to stabilize this lesion and synthesized oligonucleotides containing 2'-fluoro-N(2),3-ε-2'-deoxyarabinoguanosine to investigate the miscoding potential of N(2),3-εG by Y-family human DNA polymerases (pols). In primer extension assays, pol η and pol κ replicated through N(2),3-εG, whereas pol ι and REV1 yielded only 1-base incorporation. Steady-state kinetics revealed that dCTP incorporation is preferred opposite N(2),3-εG with relative efficiencies in the order of pol κ > REV1 > pol η ≈ pol ι, and dTTP misincorporation is the major miscoding event by all four Y-family human DNA pols. Pol ι had the highest dTTP misincorporation frequency (0.71) followed by pol η (0.63). REV1 misincorporated dTTP and dGTP with much lower frequencies. Crystal structures of pol ι with N(2),3-εG paired to dCTP and dTTP revealed Hoogsteen-like base pairing mechanisms. Two hydrogen bonds were observed in the N(2),3-εG:dCTP base pair, whereas only one appears to be present in the case of the N(2),3-εG:dTTP pair. Base pairing mechanisms derived from the crystal structures explain the slightly favored dCTP insertion for pol ι in steady-state kinetic analysis. Taken together, these results provide a basis for the mutagenic potential of N(2),3-εG.

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Organizational Affiliation: 
• Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146; Department of Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
Department of Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146; Department of Chemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
Northwestern University Synchrotron Research Center, Life Sciences Collaborative Access Team, Argonne, Illinois 60439.
Division of Pharmacology, Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Gyeonggi-do 440-746, Republic of Korea.
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146; Department of Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146. Electronic address: f.guengerich@vanderbilt.edu.
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