2PAJ

Crystal structure of an amidohydrolase from an environmental sample of Sargasso sea


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.234 
  • R-Value Observed: 0.234 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Discovery and structure determination of the orphan enzyme isoxanthopterin deaminase.

Hall, R.S.Agarwal, R.Hitchcock, D.Sauder, J.M.Burley, S.K.Swaminathan, S.Raushel, F.M.

(2010) Biochemistry 49: 4374-4382

  • DOI: 10.1021/bi100252s
  • Primary Citation of Related Structures:  
    2PAJ

  • PubMed Abstract: 
  • Two previously uncharacterized proteins have been identified that efficiently catalyze the deamination of isoxanthopterin and pterin 6-carboxylate. The genes encoding these two enzymes, NYSGXRC-9339a ( gi|44585104 ) and NYSGXRC-9236b ( gi|44611670 ), were first identified from DNA isolated from the Sargasso Sea as part of the Global Ocean Sampling Project ...

    Two previously uncharacterized proteins have been identified that efficiently catalyze the deamination of isoxanthopterin and pterin 6-carboxylate. The genes encoding these two enzymes, NYSGXRC-9339a ( gi|44585104 ) and NYSGXRC-9236b ( gi|44611670 ), were first identified from DNA isolated from the Sargasso Sea as part of the Global Ocean Sampling Project. The genes were synthesized, and the proteins were subsequently expressed and purified. The X-ray structure of Sgx9339a was determined at 2.7 A resolution (Protein Data Bank entry 2PAJ ). This protein folds as a distorted (beta/alpha)(8) barrel and contains a single zinc ion in the active site. These enzymes are members of the amidohydrolase superfamily and belong to cog0402 within the clusters of orthologous groups (COG). Enzymes in cog0402 have previously been shown to catalyze the deamination of guanine, cytosine, S-adenosylhomocysteine, and 8-oxoguanine. A small compound library of pteridines, purines, and pyrimidines was used to probe catalytic activity. The only substrates identified in this search were isoxanthopterin and pterin 6-carboxylate. The kinetic constants for the deamination of isoxanthopterin with Sgx9339a were determined to be 1.0 s(-1), 8.0 muM, and 1.3 x 10(5) M(-1) s(-1) (k(cat), K(m), and k(cat)/K(m), respectively). The active site of Sgx9339a most closely resembles the active site for 8-oxoguanine deaminase (Protein Data Bank entry 2UZ9 ). A model for substrate recognition of isoxanthopterin by Sgx9339a was proposed on the basis of the binding of guanine and xanthine in the active site of guanine deaminase. Residues critical for substrate binding appear to be conserved glutamine and tyrosine residues that form hydrogen bonds with the carbonyl oxygen at C4, a conserved threonine residue that forms hydrogen bonds with N5, and another conserved threonine residue that forms hydrogen bonds with the carbonyl group at C7. These conserved active site residues were used to identify 24 other genes which are predicted to deaminate isoxanthopterin.


    Organizational Affiliation

    Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
putative cytosine/guanine deaminaseA492unidentifiedMutation(s): 0 
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download Ideal Coordinates CCD File 
B [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.234 
  • R-Value Observed: 0.234 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 88.872α = 90
b = 88.872β = 90
c = 161.867γ = 120
Software Package:
Software NamePurpose
CNSrefinement
CBASSdata collection
HKL-2000data reduction
HKL-2000data scaling
SHARPphasing
SHELXDphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-04-03
    Type: Initial release
  • Version 1.1: 2007-10-16
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2021-02-03
    Changes: Database references, Derived calculations, Structure summary