2HHQ

O6-methyl-guanine:T pair in the polymerase-10 basepair position


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.212 

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This is version 2.0 of the entry. See complete history


Literature

The structural basis for the mutagenicity of O6-methyl-guanine lesions.

Warren, J.J.Forsberg, L.J.Beese, L.S.

(2006) Proc Natl Acad Sci U S A 103: 19701-19706

  • DOI: 10.1073/pnas.0609580103
  • Primary Citation of Related Structures:  
    2HHQ, 2HHS, 2HHT, 2HHU, 2HHV, 2HHW, 2HHX, 2HVH, 2HVI, 2HW3

  • PubMed Abstract: 
  • Methylating agents are widespread environmental carcinogens that generate a broad spectrum of DNA damage. Methylation at the guanine O(6) position confers the greatest mutagenic and carcinogenic potential. DNA polymerases insert cytosine and thymine with similar efficiency opposite O(6)-methyl-guanine (O6MeG) ...

    Methylating agents are widespread environmental carcinogens that generate a broad spectrum of DNA damage. Methylation at the guanine O(6) position confers the greatest mutagenic and carcinogenic potential. DNA polymerases insert cytosine and thymine with similar efficiency opposite O(6)-methyl-guanine (O6MeG). We combined pre-steady-state kinetic analysis and a series of nine x-ray crystal structures to contrast the reaction pathways of accurate and mutagenic replication of O6MeG in a high-fidelity DNA polymerase from Bacillus stearothermophilus. Polymerases achieve substrate specificity by selecting for nucleotides with shape and hydrogen-bonding patterns that complement a canonical DNA template. Our structures reveal that both thymine and cytosine O6MeG base pairs evade proofreading by mimicking the essential molecular features of canonical substrates. The steric mimicry depends on stabilization of a rare cytosine tautomer in C.O6MeG-polymerase complexes. An unusual electrostatic interaction between O-methyl protons and a thymine carbonyl oxygen helps stabilize T.O6MeG pairs bound to DNA polymerase. Because DNA methylators constitute an important class of chemotherapeutic agents, the molecular mechanisms of replication of these DNA lesions are important for our understanding of both the genesis and treatment of cancer.


    Organizational Affiliation

    Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, NC 27710, USA.



Macromolecules

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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
DNA polymerase IC [auth A]580Geobacillus stearothermophilusMutation(s): 0 
Gene Names: polA
EC: 2.7.7.7
UniProt
Find proteins for Q45458 (Geobacillus stearothermophilus)
Explore Q45458 
Go to UniProtKB:  Q45458
Protein Feature View
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  • Reference Sequence

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Entity ID: 1
MoleculeChainsLengthOrganismImage
5'-D(*CP*AP*TP*(6OG)P*CP*GP*AP*GP*TP*CP*AP*GP*G)-3'A [auth B]13N/A
Protein Feature View
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  • Reference Sequence

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Entity ID: 2
MoleculeChainsLengthOrganismImage
5'-D(*GP*CP*CP*TP*GP*AP*CP*TP*CP*GP*TP*AP*TP*GP*A)-3'B [auth C]15N/A
Protein Feature View
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  • Reference Sequence
Oligosaccharides

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Entity ID: 4
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
beta-D-fructofuranose-(2-1)-alpha-D-glucopyranoseD, E, F2N/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G05551OP
GlyCosmos:  G05551OP
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download Ideal Coordinates CCD File 
G [auth A], H [auth A], I [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
MG
Query on MG

Download Ideal Coordinates CCD File 
J [auth A]MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Biologically Interesting Molecules (External Reference) 1 Unique
Entity ID: 4
IDChainsNameType/Class2D Diagram3D Interactions
PRD_900003
Query on PRD_900003
D, E, FsucroseOligosaccharide / Nutrient Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.212 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86.792α = 90
b = 93.274β = 90
c = 106.018γ = 90
Software Package:
Software NamePurpose
XSCALEdata processing
CNSrefinement
PDB_EXTRACTdata extraction
XDSdata reduction
XSCALEdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-12-12
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary