4P2H

Structure of human DNA polymerase complexed with N7MG in the template opposite to incoming non-hydrolyzable TTP with manganese in the active site


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.99 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.206 

Starting Model: experimental
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This is version 1.7 of the entry. See complete history


Literature

Transition-state destabilization reveals how human DNA polymerase beta proceeds across the chemically unstable lesion N7-methylguanine.

Koag, M.C.Kou, Y.Ouzon-Shubeita, H.Lee, S.

(2014) Nucleic Acids Res 42: 8755-8766

  • DOI: https://doi.org/10.1093/nar/gku554
  • Primary Citation of Related Structures:  
    4O5C, 4O5E, 4O5K, 4P2H

  • PubMed Abstract: 

    N7-Methyl-2'-deoxyguanosine (m7dG) is the predominant lesion formed by methylating agents. A systematic investigation on the effect of m7dG on DNA replication has been difficult due to the chemical instability of m7dG. To gain insights into the m7dG effect, we employed a 2'-fluorine-mediated transition-state destabilzation strategy. Specifically, we determined kinetic parameters for dCTP insertion opposite a chemically stable m7dG analogue, 2'-fluoro-m7dG (Fm7dG), by human DNA polymerase β (polβ) and solved three X-ray structures of polβ in complex with the templating Fm7dG paired with incoming dCTP or dTTP analogues. The kinetic studies reveal that the templating Fm7dG slows polβ catalysis ∼ 300-fold, suggesting that m7dG in genomic DNA may impede replication by some DNA polymerases. The structural analysis reveals that Fm7dG forms a canonical Watson-Crick base pair with dCTP, but metal ion coordination is suboptimal for catalysis in the polβ-Fm7dG:dCTP complex, which partially explains the slow insertion of dCTP opposite Fm7dG by polβ. In addition, the polβ-Fm7dG:dTTP structure shows open protein conformations and staggered base pair conformations, indicating that N7-methylation of dG does not promote a promutagenic replication. Overall, the first systematic studies on the effect of m7dG on DNA replication reveal that polβ catalysis across m7dG is slow, yet highly accurate.


  • Organizational Affiliation

    Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA SeongminLee@austin.utexas.edu.


Macromolecules

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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase beta326Homo sapiensMutation(s): 0 
Gene Names: POLB
EC: 2.7.7.7
UniProt & NIH Common Fund Data Resources
Find proteins for P06746 (Homo sapiens)
Go to UniProtKB:  P06746
PHAROS:  P06746
GTEx:  ENSG00000070501 
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*(FMG)P*TP*CP*GP*CP*AP*TP*CP*AP*GP*C)-3')B [auth T]16Homo sapiens
Sequence Annotations
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  • Reference Sequence

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Entity ID: 3
MoleculeChains LengthOrganismImage
DNA (5'-D(*GP*CP*TP*GP*AP*TP*GP*CP*GP*A)-3')C [auth P]10Homo sapiens
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')5Homo sapiens
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.99 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.206 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.767α = 90
b = 79.167β = 106.18
c = 54.982γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
PHENIXrefinement

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of Environmental Health Sciences (NIH/NIEHS)United StatesES23101

Revision History  (Full details and data files)

  • Version 1.0: 2014-06-25
    Type: Initial release
  • Version 1.1: 2014-07-09
    Changes: Database references
  • Version 1.2: 2014-10-01
    Changes: Database references
  • Version 1.3: 2015-01-07
    Changes: Database references
  • Version 1.4: 2017-09-20
    Changes: Author supporting evidence, Database references, Derived calculations, Other, Refinement description, Source and taxonomy
  • Version 1.5: 2017-09-27
    Changes: Refinement description
  • Version 1.6: 2019-12-18
    Changes: Author supporting evidence
  • Version 1.7: 2023-09-27
    Changes: Data collection, Database references, Derived calculations, Refinement description