1qk4: Difference between revisions

Revision as of 06:22, 3 May 2008

TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE IMP COMPLEX

OverviewOverview

The crystal structures of the guanosine 5'-monophosphate (GMP) and inosine 5'-monophosphate (IMP) complexes of Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase (HGPRT) have been determined at 1.65 and 1.90 A resolution. These complexes, which crystallize in space groups P2(1) (a = 65.45 A, b = 90.84 A, c = 80. 26 A, and beta = 92.53 degrees ) and P2(1)2(1)2(1) (a = 84.54 A, b = 102.44 A, and c = 108.83 A), each comprise a tetramer in the crystallographic asymmetric unit. All active sites in the tetramers are fully occupied by the nucleotide. Comparison of these structures with that of the xanthosine 5'-monophosphate (XMP)-pyrophosphate-Mg(2+) ternary complex reported in the following article [Heroux, A., et al. (1999) Biochemistry 38, 14495-14506] shows how T. gondii HGPRT is able to recognize guanine, hypoxanthine, and xanthine as substrates, and suggests why the human enzyme cannot use xanthine efficiently. Comparison with the apoenzyme reveals the structural changes that occur upon binding of purines and ribose 5'-phosphate to HGPRT. Two structural features important to the HGPRT mechanism, a previously unrecognized active site loop (loop III', residues 180-184) and an active site peptide bond (Leu78-Lys79) that adopts both the cis and the trans configurations, are presented.

About this StructureAbout this Structure

1QK4 is a Single protein structure of sequence from Toxoplasma gondii. Full crystallographic information is available from OCA.

ReferenceReference

Crystal structures of the Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase-GMP and -IMP complexes: comparison of purine binding interactions with the XMP complex., Heroux A, White EL, Ross LJ, Borhani DW, Biochemistry. 1999 Nov 2;38(44):14485-94. PMID:10545170 Page seeded by OCA on Sat May 3 06:22:12 2008

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OCA

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 [[Image:1qk4.gif|left|200px]]
- {{Structure
+<!--
-|PDB= 1qk4 |SIZE=350|CAPTION= <scene name='initialview01'>1qk4</scene>, resolution 1.9&Aring;
+The line below this paragraph, containing "STRUCTURE_1qk4", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=IMP:INOSINIC+ACID'>IMP</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Hypoxanthine_phosphoribosyltransferase Hypoxanthine phosphoribosyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.2.8 2.4.2.8] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1qk4|  PDB=1qk4  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1qk4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qk4 OCA], [http://www.ebi.ac.uk/pdbsum/1qk4 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1qk4 RCSB]</span>
-}}
 '''TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE IMP COMPLEX'''
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 [[Category: Ross, L J.]]
 [[Category: White, E L.]]
-[[Category: glycosyltransferase]]
+[[Category: Glycosyltransferase]]
-[[Category: purine salvage]]
+[[Category: Purine salvage]]
-[[Category: transferase]]
+[[Category: Transferase]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 06:22:12 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 23:14:48 2008''