3OSN

Structural Basis for Proficient Incorporation of dTTP Opposite O6-Methylguanine by Human DNA Polymerase Iota


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.208 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural Basis for Proficient Incorporation of dTTP Opposite O6-Methylguanine by Human DNA Polymerase {iota}.

Pence, M.G.Choi, J.Y.Egli, M.Guengerich, F.P.

(2010) J.Biol.Chem. 285: 40666-40672

  • DOI: 10.1074/jbc.M110.183665
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • O(6)-methylguanine (O(6)-methylG) is highly mutagenic and is commonly found in DNA exposed to methylating agents, even physiological ones (e.g. S-adenosylmethionine). The efficiency of a truncated, catalytic DNA polymerase ι core enzyme was determine ...

    O(6)-methylguanine (O(6)-methylG) is highly mutagenic and is commonly found in DNA exposed to methylating agents, even physiological ones (e.g. S-adenosylmethionine). The efficiency of a truncated, catalytic DNA polymerase ι core enzyme was determined for nucleoside triphosphate incorporation opposite O(6)-methylG, using steady-state kinetic analyses. The results presented here corroborate previous work from this laboratory using full-length pol ι, which showed that dTTP incorporation occurs with high efficiency opposite O(6)-methylG. Misincorporation of dTTP opposite O(6)-methylG occurred with ∼6-fold higher efficiency than incorporation of dCTP. Crystal structures of the truncated form of pol ι with O(6)-methylG as the template base and incoming dCTP or dTTP were solved and showed that O(6)-methylG is rotated into the syn conformation in the pol ι active site and that dTTP misincorporation by pol ι is the result of Hoogsteen base pairing with the adduct. Both dCTP and dTTP base paired with the Hoogsteen edge of O(6)-methylG. A single, short hydrogen bond formed between the N3 atom of dTTP and the N7 atom of O(6)-methylG. Protonation of the N3 atom of dCTP and bifurcation of the N3 hydrogen between the N7 and O(6) atoms of O(6)-methylG allow base pairing of the lesion with dCTP. We conclude that differences in the Hoogsteen hydrogen bonding between nucleotides is the main factor in the preferential selectivity of dTTP opposite O(6)-methylG by human pol ι, in contrast to the mispairing modes observed previously for O(6)-methylG in the structures of the model DNA polymerases Sulfolobus solfataricus Dpo4 and Bacillus stearothermophilus DNA polymerase I.


    Organizational Affiliation

    Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure


Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
DNA polymerase iota
A
420Homo sapiensGene Names: POLI (RAD30B)
EC: 2.7.7.7
Find proteins for Q9UNA4 (Homo sapiens)
Go to Gene View: POLI
Go to UniProtKB:  Q9UNA4
Entity ID: 1
MoleculeChainsLengthOrganism
5'-D(*TP*CP*TP*(6OG)P*GP*GP*GP*TP*CP*CP*TP*AP*GP*GP*AP*CP*CP*(DOC))-3'B,C18N/A
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

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Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
TTP
Query on TTP

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Download CCD File 
A
THYMIDINE-5'-TRIPHOSPHATE
C10 H17 N2 O14 P3
NHVNXKFIZYSCEB-XLPZGREQSA-N
 Ligand Interaction
MG
Query on MG

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Download CCD File 
A
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
DOC
Query on DOC
B, C
DNA LINKINGC9 H14 N3 O6 PDC
6OG
Query on 6OG
B, C
DNA LINKINGC11 H16 N5 O7 PDG
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.208 
  • Space Group: P 65 2 2
Unit Cell:
Length (Å)Angle (°)
a = 97.973α = 90.00
b = 97.973β = 90.00
c = 202.757γ = 120.00
Software Package:
Software NamePurpose
ADSCdata collection
HKL-3000data reduction
HKL-3000data scaling
PHASERphasing
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

  • Deposited Date: 2010-09-09 
  • Released Date: 2010-10-20 
  • Deposition Author(s): Pence, M.G.

Revision History 

  • Version 1.0: 2010-10-20
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance