6U17

Human thymine DNA glycosylase bound to DNA with 2'-F-5-carboxyl-dC substrate analog


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.191 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Excision of 5-Carboxylcytosine by Thymine DNA Glycosylase.

Pidugu, L.S.Dai, Q.Malik, S.S.Pozharski, E.Drohat, A.C.

(2019) J Am Chem Soc 141: 18851-18861

  • DOI: 10.1021/jacs.9b10376
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • 5-Methylcytosine (mC) is an epigenetic mark that is written by methyltransferases, erased through passive and active mechanisms, and impacts transcription, development, diseases including cancer, and aging. Active DNA demethylation involves TET-media ...

    5-Methylcytosine (mC) is an epigenetic mark that is written by methyltransferases, erased through passive and active mechanisms, and impacts transcription, development, diseases including cancer, and aging. Active DNA demethylation involves TET-mediated stepwise oxidation of mC to 5-hydroxymethylcytosine, 5-formylcytosine (fC), or 5-carboxylcytosine (caC), excision of fC or caC by thymine DNA glycosylase (TDG), and subsequent base excision repair. Many elements of this essential process are poorly defined, including TDG excision of caC. To address this problem, we solved high-resolution structures of human TDG bound to DNA with cadC (5-carboxyl-2'-deoxycytidine) flipped into its active site. The structures unveil detailed enzyme-substrate interactions that mediate recognition and removal of caC, many involving water molecules. Importantly, two water molecules contact a carboxylate oxygen of caC and are poised to facilitate acid-catalyzed caC excision. Moreover, a substrate-dependent conformational change in TDG modulates the hydrogen bond interactions for one of these waters, enabling productive interaction with caC. An Asn residue (N191) that is critical for caC excision is found to contact N3 and N4 of caC, suggesting a mechanism for acid-catalyzed base excision that features an N3-protonated form of caC but would be ineffective for C, mC, or hmC. We also investigated another Asn residue (N140) that is catalytically essential and strictly conserved in the TDG-MUG enzyme family. A structure of N140A-TDG bound to cadC DNA provides the first high-resolution insight into how enzyme-substrate interactions, including water molecules, are impacted by depleting the conserved Asn, informing its role in binding and addition of the nucleophilic water molecule.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology , University of Maryland School of Medicine , Baltimore , Maryland 21201 , United States.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
G/T mismatch-specific thymine DNA glycosylase
A
227Homo sapiensMutation(s): 0 
Gene Names: TDG
EC: 3.2.2.29
Find proteins for Q13569 (Homo sapiens)
Go to UniProtKB:  Q13569
NIH Common Fund Data Resources
PHAROS  Q13569

Find similar nucleic acids by: Sequence  |  Structure

Entity ID: 2
MoleculeChainsLengthOrganism
DNA (28-MER)C28synthetic construct

Find similar nucleic acids by: Sequence  |  Structure

Entity ID: 3
MoleculeChainsLengthOrganism
DNA (30-MER)D28synthetic construct
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CSO
Query on CSO
A
L-PEPTIDE LINKINGC3 H7 N O3 SCYS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.189 
  • R-Value Observed: 0.191 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 96.87α = 90
b = 52.76β = 95.25
c = 81.62γ = 90
Software Package:
Software NamePurpose
BUSTERrefinement
MOSFLMdata reduction
Aimlessdata scaling
PHASERphasing
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Human Genome Research Institute (NIH/NHGRI)United States--

Revision History 

  • Version 1.0: 2019-11-20
    Type: Initial release
  • Version 1.1: 2019-12-11
    Changes: Database references
  • Version 1.2: 2019-12-18
    Changes: Author supporting evidence