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==TERNARY COMPLEX STRUCTURE OF HUMAN HGPRTASE, PRPP, MG2+, AND THE INHIBITOR HPP REVEALS THE INVOLVEMENT OF THE FLEXIBLE LOOP IN SUBSTRATE BINDING== | |||
<StructureSection load='1d6n' size='340' side='right' caption='[[1d6n]], [[Resolution|resolution]] 2.70Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[1d6n]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1D6N OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1D6N FirstGlance]. <br> | |||
==Disease== | </td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=PPO:3H-PYRAZOLO[4,3-D]PYRIMIDIN-7-OL'>PPO</scene>, <scene name='pdbligand=PRP:ALPHA-PHOSPHORIBOSYLPYROPHOSPHORIC+ACID'>PRP</scene><br> | ||
[[http://www.uniprot.org/uniprot/HPRT_HUMAN HPRT_HUMAN]] Defects in HPRT1 are the cause of Lesch-Nyhan syndrome (LNS) [MIM:[http://omim.org/entry/300322 300322]]. LNS is characterized by complete lack of enzymatic activity that results in hyperuricemia, choreoathetosis, mental retardation, and compulsive self-mutilation.<ref>PMID:6853716</ref><ref>PMID:3384338</ref><ref>PMID:3265398</ref><ref>PMID:2910902</ref><ref>PMID:2347587</ref><ref>PMID:2358296</ref><ref>PMID:2246854</ref><ref>PMID:2071157</ref><ref>PMID:7627191</ref><ref>PMID:9452051</ref> | <tr><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><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></td></tr> | ||
<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1d6n FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1d6n OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1d6n RCSB], [http://www.ebi.ac.uk/pdbsum/1d6n PDBsum]</span></td></tr> | |||
<table> | |||
== Disease == | |||
[[http://www.uniprot.org/uniprot/HPRT_HUMAN HPRT_HUMAN]] Defects in HPRT1 are the cause of Lesch-Nyhan syndrome (LNS) [MIM:[http://omim.org/entry/300322 300322]]. LNS is characterized by complete lack of enzymatic activity that results in hyperuricemia, choreoathetosis, mental retardation, and compulsive self-mutilation.<ref>PMID:6853716</ref> <ref>PMID:3384338</ref> <ref>PMID:3265398</ref> <ref>PMID:2910902</ref> <ref>PMID:2347587</ref> <ref>PMID:2358296</ref> <ref>PMID:2246854</ref> <ref>PMID:2071157</ref> <ref>PMID:7627191</ref> <ref>PMID:9452051</ref> Defects in HPRT1 are the cause of gout HPRT-related (GOUT-HPRT) [MIM:[http://omim.org/entry/300323 300323]]; also known as HPRT-related gout or Kelley-Seegmiller syndrome. Gout is characterized by partial enzyme activity and hyperuricemia.<ref>PMID:6853490</ref> <ref>PMID:6572373</ref> <ref>PMID:6706936</ref> <ref>PMID:3358423</ref> <ref>PMID:3198771</ref> <ref>PMID:2909537</ref> [:] | |||
== Function == | |||
[[http://www.uniprot.org/uniprot/HPRT_HUMAN HPRT_HUMAN]] Converts guanine to guanosine monophosphate, and hypoxanthine to inosine monophosphate. Transfers the 5-phosphoribosyl group from 5-phosphoribosylpyrophosphate onto the purine. Plays a central role in the generation of purine nucleotides through the purine salvage pathway. | |||
== Evolutionary Conservation == | |||
[[Image:Consurf_key_small.gif|200px|right]] | |||
Check<jmol> | |||
<jmolCheckbox> | |||
<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/d6/1d6n_consurf.spt"</scriptWhenChecked> | |||
<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> | |||
<text>to colour the structure by Evolutionary Conservation</text> | |||
</jmolCheckbox> | |||
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Site-directed mutagenesis was used to replace Lys68 of the human hypoxanthine phosphoribosyltransferase (HGPRTase) with alanine to exploit this less reactive form of the enzyme to gain additional insights into the structure activity relationship of HGPRTase. Although this substitution resulted in only a minimal (one- to threefold) increase in the Km values for binding pyrophosphate or phosphoribosylpyrophosphate, the catalytic efficiencies (k(cat)/Km) of the forward and reverse reactions were more severely reduced (6- to 30-fold), and the mutant enzyme showed positive cooperativity in binding of alpha-D-5-phosphoribosyl-1-pyrophosphate (PRPP) and nucleotide. The K68A form of the human HGPRTase was cocrystallized with 7-hydroxy [4,3-d] pyrazolo pyrimidine (HPP) and Mg PRPP, and the refined structure reported. The PRPP molecule built into the [(Fo - Fc)phi(calc)] electron density shows atomic interactions between the Mg PRPP and enzyme residues in the pyrophosphate binding domain as well as in a long flexible loop (residues Leu101 to Gly111) that closes over the active site. Loop closure reveals the functional roles for the conserved SY dipeptide of the loop as well as the molecular basis for one form of gouty arthritis (S103R). In addition, the closed loop conformation provides structural information relevant to the mechanism of catalysis in human HGPRTase. | |||
Ternary complex structure of human HGPRTase, PRPP, Mg2+, and the inhibitor HPP reveals the involvement of the flexible loop in substrate binding.,Balendiran GK, Molina JA, Xu Y, Torres-Martinez J, Stevens R, Focia PJ, Eakin AE, Sacchettini JC, Craig SP 3rd Protein Sci. 1999 May;8(5):1023-31. PMID:10338013<ref>PMID:10338013</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
==See Also== | ==See Also== | ||
*[[Phosphoribosyltransferase|Phosphoribosyltransferase]] | *[[Phosphoribosyltransferase|Phosphoribosyltransferase]] | ||
== References == | |||
== | <references/> | ||
__TOC__ | |||
</StructureSection> | |||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Hypoxanthine phosphoribosyltransferase]] | [[Category: Hypoxanthine phosphoribosyltransferase]] |
Revision as of 19:46, 29 September 2014
TERNARY COMPLEX STRUCTURE OF HUMAN HGPRTASE, PRPP, MG2+, AND THE INHIBITOR HPP REVEALS THE INVOLVEMENT OF THE FLEXIBLE LOOP IN SUBSTRATE BINDINGTERNARY COMPLEX STRUCTURE OF HUMAN HGPRTASE, PRPP, MG2+, AND THE INHIBITOR HPP REVEALS THE INVOLVEMENT OF THE FLEXIBLE LOOP IN SUBSTRATE BINDING
Structural highlights
Disease[HPRT_HUMAN] Defects in HPRT1 are the cause of Lesch-Nyhan syndrome (LNS) [MIM:300322]. LNS is characterized by complete lack of enzymatic activity that results in hyperuricemia, choreoathetosis, mental retardation, and compulsive self-mutilation.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Defects in HPRT1 are the cause of gout HPRT-related (GOUT-HPRT) [MIM:300323]; also known as HPRT-related gout or Kelley-Seegmiller syndrome. Gout is characterized by partial enzyme activity and hyperuricemia.[11] [12] [13] [14] [15] [16] [:] Function[HPRT_HUMAN] Converts guanine to guanosine monophosphate, and hypoxanthine to inosine monophosphate. Transfers the 5-phosphoribosyl group from 5-phosphoribosylpyrophosphate onto the purine. Plays a central role in the generation of purine nucleotides through the purine salvage pathway. 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 PubMedSite-directed mutagenesis was used to replace Lys68 of the human hypoxanthine phosphoribosyltransferase (HGPRTase) with alanine to exploit this less reactive form of the enzyme to gain additional insights into the structure activity relationship of HGPRTase. Although this substitution resulted in only a minimal (one- to threefold) increase in the Km values for binding pyrophosphate or phosphoribosylpyrophosphate, the catalytic efficiencies (k(cat)/Km) of the forward and reverse reactions were more severely reduced (6- to 30-fold), and the mutant enzyme showed positive cooperativity in binding of alpha-D-5-phosphoribosyl-1-pyrophosphate (PRPP) and nucleotide. The K68A form of the human HGPRTase was cocrystallized with 7-hydroxy [4,3-d] pyrazolo pyrimidine (HPP) and Mg PRPP, and the refined structure reported. The PRPP molecule built into the [(Fo - Fc)phi(calc)] electron density shows atomic interactions between the Mg PRPP and enzyme residues in the pyrophosphate binding domain as well as in a long flexible loop (residues Leu101 to Gly111) that closes over the active site. Loop closure reveals the functional roles for the conserved SY dipeptide of the loop as well as the molecular basis for one form of gouty arthritis (S103R). In addition, the closed loop conformation provides structural information relevant to the mechanism of catalysis in human HGPRTase. Ternary complex structure of human HGPRTase, PRPP, Mg2+, and the inhibitor HPP reveals the involvement of the flexible loop in substrate binding.,Balendiran GK, Molina JA, Xu Y, Torres-Martinez J, Stevens R, Focia PJ, Eakin AE, Sacchettini JC, Craig SP 3rd Protein Sci. 1999 May;8(5):1023-31. PMID:10338013[17] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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