7S9J

Crystal Structure of DNA Polymerase Beta with Fapy-dG base-paired with a dC


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.91 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.191 

Starting Model: experimental
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Literature

Structural Dynamics of a Common Mutagenic Oxidative DNA Lesion in Duplex DNA and during DNA Replication.

Ryan, B.J.Yang, H.Bacurio, J.H.T.Smith, M.R.Basu, A.K.Greenberg, M.M.Freudenthal, B.D.

(2022) J Am Chem Soc 144: 8054-8065

  • DOI: https://doi.org/10.1021/jacs.2c00193
  • Primary Citation of Related Structures:  
    7S9J, 7S9K, 7S9L, 7S9M, 7S9N, 7S9O, 7S9P, 7S9Q

  • PubMed Abstract: 

    N 6-(2-Deoxy-α,β-d- erythro -pentofuranosyl)-2,6-diamino-4-hydroxy-5-formamido pyrimidine (Fapy•dG) is a prevalent form of genomic DNA damage. Fapy•dG is formed in greater amounts under anoxic conditions than the well-studied, chemically related 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodGuo). Fapy•dG is more mutagenic in mammalian cells than 8-oxodGuo. A distinctive property of Fapy•dG is facile epimerization, but prior works with Fapy•dG analogues have precluded determining its effect on chemistry. We present crystallographic characterization of natural Fapy•dG in duplex DNA and as the template base for DNA polymerase β (Pol β). Fapy•dG adopts the β-anomer when base paired with cytosine but exists as a mixture of α- and β-anomers when promutagenically base paired with adenine. Rotation about the bond between the glycosidic nitrogen atom and the pyrimidine ring is also affected by the opposing nucleotide. Sodium cyanoborohydride soaking experiments trap the ring-opened Fapy•dG, demonstrating that ring opening and epimerization occur in the crystalline state. Ring opening and epimerization are facilitated by propitious water molecules that are observed in the structures. Determination of Fapy•dG mutagenicity in wild type and Pol β knockdown HEK 293T cells indicates that Pol β contributes to G → T transversions but also suppresses G → A transitions. Complementary kinetic studies have determined that Fapy•dG promotes mutagenesis by decreasing the catalytic efficiency of dCMP insertion opposite Fapy•dG, thus reducing polymerase fidelity. Kinetic studies have determined that dCMP incorporation opposite the β-anomer is ∼90 times faster than the α-anomer. This research identifies the importance of anomer dynamics, a feature unique to formamidopyrimidines, when considering the incorporation of nucleotides opposite Fapy•dG and potentially the repair of this structurally unusual lesion.


  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, United States.


Macromolecules

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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase beta335Homo sapiensMutation(s): 0 
Gene Names: POLB
EC: 2.7.7.7 (PDB Primary Data), 4.2.99 (PDB Primary Data), 4.2.99.18 (UniProt)
UniProt & NIH Common Fund Data Resources
Find proteins for P06746 (Homo sapiens)
Explore P06746 
Go to UniProtKB:  P06746
PHAROS:  P06746
GTEx:  ENSG00000070501 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06746
Sequence Annotations
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  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
DNA (5'-D(*CP*CP*GP*AP*CP*GP*GP*CP*GP*CP*AP*TP*(FAP)P*AP*GP*C)-3')B [auth T]16synthetic construct
Sequence Annotations
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  • Reference Sequence

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Entity ID: 3
MoleculeChains LengthOrganismImage
DNA (5'-D(*GP*CP*TP*CP*AP*TP*GP*CP*GP*C)-3')C [auth P]10synthetic construct
Sequence Annotations
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  • Reference Sequence

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Entity ID: 4
MoleculeChains LengthOrganismImage
DNA (5'-D(P*GP*TP*CP*GP*G)-3')5synthetic construct
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.91 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.191 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.383α = 90
b = 79.494β = 105.716
c = 54.885γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data collection
HKL-2000data scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction
PHENIXphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of Environmental Health Sciences (NIH/NIEHS)United States--

Revision History  (Full details and data files)

  • Version 1.0: 2022-08-03
    Type: Initial release
  • Version 1.1: 2023-10-18
    Changes: Data collection, Refinement description