4FS2

Base pairing mechanism of N2,3-ethenoguanine with dCTP by human polymerase iota


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.214 
  • R-Value Observed: 0.217 

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Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history


Literature

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

Zhao, L.Pence, M.G.Christov, P.P.Wawrzak, Z.Choi, J.Y.Rizzo, C.J.Egli, M.Guengerich, F.P.

(2012) J Biol Chem 287: 35516-35526

  • 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.


  • 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.


Macromolecules

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase iotaC [auth A]420Homo sapiensMutation(s): 0 
Gene Names: POLIRAD30B
EC: 2.7.7.7
UniProt & NIH Common Fund Data Resources
Find proteins for Q9UNA4 (Homo sapiens)
Explore Q9UNA4 
Go to UniProtKB:  Q9UNA4
PHAROS:  Q9UNA4
GTEx:  ENSG00000101751 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9UNA4
Sequence Annotations
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  • Reference Sequence

Find similar nucleic acids by:  Sequence   |   3D Structure  

Entity ID: 1
MoleculeChains LengthOrganismImage
DNA (5'-D(*TP*CP*TP*(EFG)P*GP*GP*GP*TP*CP*CP*TP*AP*GP*GP*AP*CP*CP*(DOC))-3')A [auth B],
B [auth C]
18synthetic construct
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.214 
  • R-Value Observed: 0.217 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 97.298α = 90
b = 97.298β = 90
c = 202.906γ = 120
Software Package:
Software NamePurpose
EMBLdata collection
MOLREPphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

  • Released Date: 2012-08-29 
  • Deposition Author(s): Zhao, L.

Revision History  (Full details and data files)

  • Version 1.0: 2012-08-29
    Type: Initial release
  • Version 1.1: 2012-09-12
    Changes: Database references
  • Version 1.2: 2012-10-31
    Changes: Database references
  • Version 1.3: 2024-02-28
    Changes: Data collection, Database references, Derived calculations