1yr3: Difference between revisions

Revision as of 16:40, 3 May 2008

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

OverviewOverview

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.

About this StructureAbout this Structure

1YR3 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

ReferenceReference

Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene., Dandanell G, Szczepanowski RH, Kierdaszuk B, Shugar D, Bochtler M, J Mol Biol. 2005 Apr 22;348(1):113-25. PMID:15808857 Page seeded by OCA on Sat May 3 16:40:34 2008

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OCA

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 [[Image:1yr3.gif|left|200px]]
- {{Structure
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+The line below this paragraph, containing "STRUCTURE_1yr3", creates the "Structure Box" on the page.
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-|LIGAND= <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>, <scene name='pdbligand=XAN:XANTHINE'>XAN</scene>
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-|GENE= xapA, pndA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
+-->
-|DOMAIN=
+{{STRUCTURE_1yr3|  PDB=1yr3  |  SCENE=  }}
-|RELATEDENTRY=[[1yqq|1YQQ]], [[1yqu|1YQU]]
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1yr3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1yr3 OCA], [http://www.ebi.ac.uk/pdbsum/1yr3 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1yr3 RCSB]</span>
-}}
 '''Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene'''
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 [[Category: Shugar, D.]]
 [[Category: Szczepanowski, R H.]]
-[[Category: purine nucleoside phosphorylase guanine xanthine]]
+[[Category: Purine nucleoside phosphorylase guanine xanthine]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 16:40:34 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 01:18:45 2008''