1YQQ

Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.240 
  • R-Value Observed: 0.241 

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This is version 1.2 of the entry. See complete history


Literature

Escherichia coli Purine Nucleoside Phosphorylase II, the Product of the xapA Gene

Dandanell, G.Szczepanowski, R.H.Kierdaszuk, B.Shugar, D.Bochtler, M.

(2005) J Mol Biol 348: 113-125

  • DOI: 10.1016/j.jmb.2005.02.019
  • Primary Citation of Related Structures:  
    1YQU, 1YR3, 1YQQ

  • PubMed Abstract: 
  • Purine nucleoside phosphorylases (PNPs, E. C. 2.4.2.1) use orthophosphate to cleave the N-glycosidic bond of beta-(deoxy)ribonucleosides to yield alpha-(deoxy)ribose 1-phosphate and the free purine base. Escherichia coli PNP-II, the product of the xapA gene, is similar to trimeric PNPs in sequence, but has been reported to migrate as a hexamer and to accept xanthosine with comparable efficiency to guanosine and inosine, the usual physiological substrates for trimeric PNPs ...

    Purine nucleoside phosphorylases (PNPs, E. C. 2.4.2.1) use orthophosphate to cleave the N-glycosidic bond of beta-(deoxy)ribonucleosides to yield alpha-(deoxy)ribose 1-phosphate and the free purine base. Escherichia coli PNP-II, the product of the xapA gene, is similar to trimeric PNPs in sequence, but has been reported to migrate as a hexamer and to accept xanthosine with comparable efficiency to guanosine and inosine, the usual physiological substrates for trimeric PNPs. Here, we present a detailed biochemical characterization and the crystal structure of E.coli PNP-II. In three different crystal forms, PNP-II trimers dimerize, leading to a subunit arrangement that is qualitatively different from the "trimer of dimers" arrangement of conventional high molecular mass PNPs. Crystal structures are compatible with similar binding modes for guanine and xanthine, with a preference for the neutral over the monoanionic form of xanthine. A single amino acid exchange, tyrosine 191 to leucine, is sufficient to convert E.coli PNP-II into an enzyme with the specificity of conventional trimeric PNPs, but the reciprocal mutation in human PNP, valine 195 to tyrosine, does not elicit xanthosine phosphorylase activity in the human enzyme.


    Organizational Affiliation

    Department of Biological Chemistry, Institute of Molecular Biology, Solvgade 83H, 1307 Copenhagen, Denmark.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Xanthosine phosphorylaseA, B, C277Escherichia coliMutation(s): 0 
Gene Names: xapA
EC: 2.4.2.1
UniProt
Find proteins for P45563 (Escherichia coli (strain K12))
Explore P45563 
Go to UniProtKB:  P45563
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.240 
  • R-Value Observed: 0.241 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 98.531α = 90
b = 116.633β = 90
c = 73.423γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
MOLREPphasing
CNSrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-04-19
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance