2IBT

Crystal structure of the adenine-specific DNA methyltransferase M.TaqI complexed with the cofactor analog AETA and a 10 bp DNA containing 2-aminopurine at the target position and an abasic site analog at the target base partner position


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.203 
  • R-Value Work: 0.167 
  • R-Value Observed: 0.169 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

2-Aminopurine Flipped into the Active Site of the Adenine-Specific DNA Methyltransferase M.TaqI: Crystal Structures and Time-Resolved Fluorescence

Lenz, T.Bonnist, E.Y.M.Pljevaljcic, G.Neely, R.K.Dryden, D.T.F.Scheidig, A.J.Jones, A.C.Weinhold, E.

(2007) J Am Chem Soc 129: 6240-6248

  • DOI: 10.1021/ja069366n
  • Primary Citation of Related Structures:  
    2IBT, 2IBS

  • PubMed Abstract: 
  • We report the crystal structure of the DNA adenine-N6 methyltransferase, M.TaqI, complexed with DNA, showing the fluorescent adenine analog, 2-aminopurine, flipped out of the DNA helix and occupying virtually the same position in the active site as t ...

    We report the crystal structure of the DNA adenine-N6 methyltransferase, M.TaqI, complexed with DNA, showing the fluorescent adenine analog, 2-aminopurine, flipped out of the DNA helix and occupying virtually the same position in the active site as the natural target adenine. Time-resolved fluorescence spectroscopy of the crystalline complex faithfully reports this state: base flipping is accompanied by the loss of the very short ( approximately 50 ps) lifetime component associated with fully base-stacked 2-aminopurine in DNA, and 2-aminopurine is subject to considerable quenching by pi-stacking interactions with Tyr108 in the catalytic motif IV (NPPY). This proves 2-aminopurine to be an excellent probe for studying base flipping by M.TaqI and suggests similar quenching in the active sites of DNA and RNA adenine-N6 as well as DNA cytosine-N4 methyltransferases sharing the conserved motif IV. In solution, the same distinctive fluorescence response confirms complete destacking from DNA and is also observed when the proposed key residue for base flipping by M.TaqI, the target base partner thymine, is substituted by an abasic site analog. The corresponding cocrystal structure shows 2-aminopurine in the active site of M.TaqI, demonstrating that the partner thymine is not essential for base flipping. However, in this structure, a shift of the 3' neighbor of the target base into the vacancy left after base flipping is observed, apparently replicating a stabilizing role of the missing partner thymine. Time-resolved fluorescence and acrylamide quenching measurements of M.TaqI complexes in solution provide evidence for an alternative binding site for the extra-helical target base within M.TaqI and suggest that the partner thymine assists in delivering the target base into the active site.


    Related Citations: 
    • Structure of the N6-adenine DNA methyltransferase M.TaqI in complex with DNA and a cofactor analog
      Goedecke, K., Pignot, M., Goody, R.S., Scheidig, A.J., Weinhold, E.
      (2001) Nat Struct Biol 8: 121
    • Differential binding of S-adenosylmethionine S-adenosylhomocysteine and Sinefungin to the adenine-specific DNA methyltransferase M.TaqI
      Schluckebier, G., Kozak, M., Bleimling, N., Weinhold, E., Saenger, W.
      (1997) J Mol Biol 265: 56

    Organizational Affiliation

    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52056 Aachen, Germany.



Macromolecules

Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Modification methylase TaqIAD421Thermus aquaticusMutation(s): 0 
Gene Names: taqIM
EC: 2.1.1.72
Find proteins for P14385 (Thermus aquaticus)
Explore P14385 
Go to UniProtKB:  P14385
Protein Feature View
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  • Reference Sequence
  • Find similar nucleic acids by:  Sequence   |   Structure
  • Entity ID: 1
    MoleculeChainsLengthOrganismImage
    5'-D(*GP*TP*TP*CP*GP*(2PR)P*TP*GP*TP*C)-3'B, E10N/A
    • Find similar nucleic acids by:  Sequence   |   Structure
    • Entity ID: 2
      MoleculeChainsLengthOrganismImage
      5'-D(*GP*AP*CP*AP*(3DR)P*CP*GP*(6MA)P*AP*C)-3'C, F10N/A
      Small Molecules
      Ligands 2 Unique
      IDChainsName / Formula / InChI Key2D Diagram3D Interactions
      NEA
      Query on NEA

      Download CCD File 
      A, D
      5'-DEOXY-5'-[2-(AMINO)ETHYLTHIO]ADENOSINE
      C12 H18 N6 O3 S
      APAPOJUCRZTCHD-WOUKDFQISA-N
       Ligand Interaction
      GOL
      Query on GOL

      Download CCD File 
      A, D
      GLYCEROL
      C3 H8 O3
      PEDCQBHIVMGVHV-UHFFFAOYSA-N
       Ligand Interaction
      External Ligand Annotations 
      IDBinding Affinity (Sequence Identity %)
      NEAKd :  500   nM  PDBBind
      Experimental Data & Validation

      Experimental Data

      • Method: X-RAY DIFFRACTION
      • Resolution: 1.70 Å
      • R-Value Free: 0.203 
      • R-Value Work: 0.167 
      • R-Value Observed: 0.169 
      • Space Group: P 1 21 1
      Unit Cell:
      Length ( Å )Angle ( ˚ )
      a = 59.339α = 90
      b = 68.699β = 92.09
      c = 114.022γ = 90
      Software Package:
      Software NamePurpose
      REFMACrefinement
      ProDCdata collection
      MAR345data collection
      XDSdata scaling
      MOLREPphasing

      Structure Validation

      View Full Validation Report



      Entry History 

      Deposition Data

      Revision History 

      • Version 1.0: 2007-05-29
        Type: Initial release
      • Version 1.1: 2008-05-01
        Changes: Version format compliance
      • Version 1.2: 2011-07-13
        Changes: Non-polymer description, Version format compliance
      • Version 1.3: 2017-10-18
        Changes: Refinement description