3KD5

Closed ternary complex of an RB69 gp43 fingers domain mutant complexed with an acyclic GMP terminated primer template pair and phosphonoformic acid.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.69 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.219 

wwPDB Validation   3D Report Full Report


This is version 1.5 of the entry. See complete history


Literature

Phosphonoformic acid inhibits viral replication by trapping the closed form of the DNA polymerase.

Zahn, K.E.Tchesnokov, E.P.Gotte, M.Doublie, S.

(2011) J Biol Chem 286: 25246-25255

  • DOI: https://doi.org/10.1074/jbc.M111.248864
  • Primary Citation of Related Structures:  
    3KD1, 3KD5

  • PubMed Abstract: 

    Phosphonoformic acid (PFA, foscarnet) belongs to a class of antiviral drugs that inhibit the human cytomegalovirus DNA polymerase (UL54) by mimicking the pyrophosphate leaving group of the nucleotide transfer reaction. Difficulties expressing UL54 have hampered investigation of the precise structural requirements rendering inhibition by this drug. However, a previously engineered chimeric DNA polymerase, constructed by mutating the homologous polymerase from bacteriophage RB69 (gp43) to express several variable elements from UL54, can bypass this obstacle because of its favorable expression and acquired sensitivity to PFA (Tchesnokov, E. P., Obikhod, A., Schinazi, R. F., and Götte, M. (2008) J. Biol. Chem. 283, 34218-34228). Here, we compare two crystal structures that depict the chimeric DNA polymerase with and without PFA bound. PFA is visualized for the first time in the active site of a DNA polymerase, where interactions are resolved between the PP(i) mimic and two basic residues absolutely conserved in the fingers domain of family B polymerases. PFA also chelates metal ion B, the cation that contacts the triphosphate tail of the incoming nucleotide. These DNA complexes utilize a primer-template pair enzymatically chain-terminated by incorporation of acyclo-GMP, the phosphorylated form of the anti-herpes drug acyclovir. We postulate that the V478W mutation present in the chimera is critical in that it pushes the fingers domain to more readily adopt the closed conformation whether or not the drug is bound. The closed state of the fingers domain traps the variant polymerase in the untranslocated state and increases affinity for PFA. This finding provides a model for the mechanism of UL54 stalling by PFA.


  • Organizational Affiliation

    Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont 05405, USA.


Macromolecules

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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymeraseC [auth E]913Escherichia phage RB69Mutation(s): 10 
Gene Names: 43RB69 gp43
EC: 2.7.7.7
UniProt
Find proteins for Q38087 (Escherichia phage RB69)
Explore Q38087 
Go to UniProtKB:  Q38087
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ38087
Sequence Annotations
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  • Reference Sequence

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Entity ID: 1
MoleculeChains LengthOrganismImage
DNA (5'-D(*CP*GP*TP*CP*TP*TP*AP*TP*GP*AP*CP*AP*GP*CP*CP*GP*CP*G)-3')A [auth T]18N/A
Sequence Annotations
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  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
DNA (5'-D(*GP*CP*GP*GP*CP*TP*GP*TP*CP*AP*TP*AP*AP*(4DG))-3')B [auth P]14N/A
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.69 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.219 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 77.855α = 90
b = 122.481β = 90
c = 133.371γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
CNSrefinement
Blu-Icedata collection
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-04-13
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2015-04-15
    Changes: Database references
  • Version 1.3: 2019-07-17
    Changes: Data collection, Derived calculations, Refinement description
  • Version 1.4: 2021-10-13
    Changes: Database references, Derived calculations, Structure summary
  • Version 1.5: 2023-09-06
    Changes: Data collection, Refinement description