1qk4

TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE IMP COMPLEX

spinqualitylabelsall models 1qk4, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1qk4 is a 4 chain structure with sequence from Toxoplasma gondii RH. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: IMP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HGXR_TOXGO Catalyzes the transfer of a ribosyl phosphate group from 5-phosphoribose 1-diphosphate to the N(9) of hypoxanthine, guanine or xanthine. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Phosphoribosyltransferase 3D structures

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