4LC5

Structural basis of substrate specificity of CDA superfamily guanine deaminase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.169 

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Literature

Structural basis of the substrate specificity of cytidine deaminase superfamily Guanine deaminase

Bitra, A.Biswas, A.Anand, R.

(2013) Biochemistry 52: 8106-8114

  • DOI: https://doi.org/10.1021/bi400818e
  • Primary Citation of Related Structures:  
    4LC5, 4LCN, 4LCO, 4LCP, 4LD2, 4LD4

  • PubMed Abstract: 

    Guanine deaminases (GDs) are important enzymes involved in purine metabolism as well as nucleotide anabolism pathways that exhibit a high degree of fidelity. Here, the structural basis of the substrate specificity of GDs was investigated by determining a series of X-ray structures of NE0047 (GD from Nitrosomonas europaea) with nucleobase analogues and nucleosides. The structures demonstrated that the interactions in the GD active site are tailor-made to accommodate only guanine and any substitutions in the purine ring or introduction of a pyrimidine ring results in rearrangement of the bases in a catalytically unfavorable orientation, away from the proton shuttling residue E143. In addition, X-ray structural studies performed on cytidine revealed that although it binds in an optimal conformation, its deamination does not occur because of the inability of the enzyme to orchestrate the closure of the catalytically important C-terminal loop (residues 181-189). Isothermal calorimetry measurements established that these nucleoside moieties also disrupt the sequential mode of ligand binding, thereby abrogating all intersubunit communication. Intriguingly, it was recently discovered that GDs can also serve as endogenous ammeline deaminases, although it is structurally nonhomologous with guanine. To understand the mechanism of dual-substrate specificity, the structure of NE0047 in complex with ammeline was determined to a resolution of 2.7 Å. The structure revealed that ammeline not only fits in the active site in a catalytically favorable orientation but also allows for closure of the C-terminal loop.


  • Organizational Affiliation

    Department of Chemistry, Indian Institute of Technology , Mumbai 400076, India.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cytidine and deoxycytidylate deaminase zinc-binding region
A, B
197Nitrosomonas europaea ATCC 19718Mutation(s): 0 
EC: 3.5
UniProt
Find proteins for Q82Y41 (Nitrosomonas europaea (strain ATCC 19718 / CIP 103999 / KCTC 2705 / NBRC 14298))
Explore Q82Y41 
Go to UniProtKB:  Q82Y41
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ82Y41
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.169 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.15α = 90
b = 74.18β = 90
c = 109.78γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
PDB_EXTRACTdata extraction
iMOSFLMdata reduction

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-01-22
    Type: Initial release