3hk8: Difference between revisions
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[[Image: | ==Crystal structure of uronate isomerase from Bacillus halodurans complexed with zinc and D-Arabinohydroxamate== | ||
<StructureSection load='3hk8' size='340' side='right' caption='[[3hk8]], [[Resolution|resolution]] 2.20Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[3hk8]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Bacillus_halodurans_c-125 Bacillus halodurans c-125]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3HK8 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3HK8 FirstGlance]. <br> | |||
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=CO3:CARBONATE+ION'>CO3</scene>, <scene name='pdbligand=HDL:D-ARABINOHYDROXAMIC+ACID'>HDL</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr> | |||
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2q08|2q08]], [[2q6e|2q6e]], [[3hk5|3hk5]], [[3hk7|3hk7]], [[3hk9|3hk9]], [[3hka|3hka]]</td></tr> | |||
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">BH0493 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=272558 Bacillus halodurans C-125])</td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3hk8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3hk8 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3hk8 RCSB], [http://www.ebi.ac.uk/pdbsum/3hk8 PDBsum]</span></td></tr> | |||
</table> | |||
== 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/hk/3hk8_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 == | |||
Uronate isomerase (URI) catalyzes the reversible isomerization of D-glucuronate to D-fructuronate and of D-galacturonate to D-tagaturonate. URI is a member of the amidohydrolase superfamily (AHS), a highly divergent group of enzymes that catalyzes primarily hydrolytic reactions. The chemical mechanism and active site structure of URI was investigated in an attempt to obtain a greater understanding of how an active site template that apparently evolved to catalyze hydrolytic reactions has been re-forged to catalyze an isomerization reaction. The pH-rate profiles for kcat and kcat/Km for URI from Escherichia coli are bell-shaped and indicate that one group must be unprotonated and another residue must be protonated for catalytic activity. Primary isotope effects on the kinetic constants with [2-2H]-D-glucuronate and the effects of changes in solvent viscosity are consistent with product release as the rate limiting step. The X-ray structure of Bh0493, a URI from Bacillus halodurans, was determined in the presence of the substrate D-glucuronate. The bound complex showed that the mononuclear metal center in the active site is ligated to the C-6 carboxylate and the C-5 hydroxyl group of the substrate. This hydroxyl group is also hydrogen bonded to Asp-355 in the same orientation as the hydroxide/water is bound in those members of the AHS that catalyze hydrolytic reactions. In addition, the C-2 and C-3 hydroxyl groups of the substrate are hydrogen bonded to Arg-357 and the carbonyl group at C-1 is hydrogen bonded to Tyr-50. A chemical mechanism is proposed that utilizes a proton transfer from C-2 of D-glucuronate to C-1 that is initiated by the combined actions of Asp-355 from the end of beta-strand 8 and the C-5 hydroxyl of the substrate that is bound to the metal ion. The formation of the cis-enediol intermediate is further facilitated by the shuttling of the proton between the C-2 and C-1 oxygens by the conserved Tyr-50 and/or Arg-355. | |||
The Mechanism of the Reaction Catalyzed by Uronate Isomerase Illustrates How an Isomerase May Have Evolved from a Hydrolase within the Amidohydrolase Superfamily.,Nguyen TT, Fedorov AA, Williams L, Fedorov EV, Li Y, Xu C, Almo SC, Raushel FM Biochemistry. 2009 Aug 14. PMID:19678710<ref>PMID:19678710</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
== | |||
< | |||
[[Category: Bacillus halodurans c-125]] | [[Category: Bacillus halodurans c-125]] | ||
[[Category: Almo, S C | [[Category: Almo, S C]] | ||
[[Category: Fedorov, A A | [[Category: Fedorov, A A]] | ||
[[Category: Fedorov, E V | [[Category: Fedorov, E V]] | ||
[[Category: Nguyen, T T | [[Category: Nguyen, T T]] | ||
[[Category: Raushel, F M | [[Category: Raushel, F M]] | ||
[[Category: D-arabinohydroxamate]] | [[Category: D-arabinohydroxamate]] | ||
[[Category: Isomerase]] | [[Category: Isomerase]] | ||
[[Category: Mechanism of the reaction]] | [[Category: Mechanism of the reaction]] | ||
[[Category: Uronate isomerase]] | [[Category: Uronate isomerase]] | ||