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| [[Image:2ioh.jpg|left|200px]]<br /><applet load="2ioh" size="350" color="white" frame="true" align="right" spinBox="true"
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| caption="2ioh, resolution 2.90Å" />
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| '''Crystal structure of phosphonoacetaldehyde hydrolase with a K53R mutation'''<br />
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| ==Overview== | | ==Crystal structure of phosphonoacetaldehyde hydrolase with a K53R mutation== |
| Phosphonatase functions in the 2-aminoethylphosphonate (AEP) degradation, pathway of bacteria, catalyzing the hydrolysis of the C-P bond in, phosphonoacetaldehyde (Pald) via formation of a bi-covalent, Lys53ethylenamine/Asp12 aspartylphosphate intermediate. Because, phosphonatase is a member of the haloacid dehalogenase superfamily, a, family predominantly comprised of phosphatases, the question arises as to, how this new catalytic activity evolved. The source of general acid-base, catalysis for Schiff-base formation and aspartylphosphate hydrolysis was, probed using pH-rate profile analysis of active-site mutants and X-ray, crystallographic analysis of modified forms of the enzyme. The 2.9 A X-ray, crystal structure of the mutant Lys53Arg complexed with Mg2+ and phosphate, shows that the equilibrium between the open and the closed conformation is, disrupted, favoring the open conformation. Thus, proton dissociation from, the cap domain Lys53 is required for cap domain-core domain closure. The, likely recipient of the Lys53 proton is a water-His56 pair that serves to, relay the proton to the carbonyl oxygen of the phosphonoacetaldehyde, (Pald) substrate upon addition of the Lys53. The pH-rate profile analysis, of active-site mutants was carried out to test this proposal. The proximal, core domain residues Cys22 and Tyr128 were ruled out, and the role of cap, domain His56 was supported by the results. The X-ray crystallographic, structure of wild-type phosphonatase reduced with NaBH4 in the presence of, Pald was determined at 2.4A resolution to reveal N epsilon-ethyl-Lys53, juxtaposed with a sulfate ligand bound in the phosphate site. The position, of the C2 of the N-ethyl group in this structure is consistent with the, hypothesis that the cap domain N epsilon-ethylenamine-Lys53 functions as a, general base in the hydrolysis of the aspartylphosphate bi-covalent enzyme, intermediate. Because the enzyme residues proposed to play a key role in, P-C bond cleavage are localized on the cap domain, this domain appears to, have evolved to support the diversification of the HAD phosphatase core, domain for catalysis of hydrolytic P-C bond cleavage.
| | <StructureSection load='2ioh' size='340' side='right'caption='[[2ioh]], [[Resolution|resolution]] 2.90Å' scene=''> |
| | | == Structural highlights == |
| ==About this Structure== | | <table><tr><td colspan='2'>[[2ioh]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_cereus Bacillus cereus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IOH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2IOH FirstGlance]. <br> |
| 2IOH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_cereus Bacillus cereus] with <scene name='pdbligand=PO4:'>PO4</scene> and <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2IOH OCA].
| | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.9Å</td></tr> |
| | | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr> |
| ==Reference== | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2ioh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ioh OCA], [https://pdbe.org/2ioh PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ioh RCSB], [https://www.ebi.ac.uk/pdbsum/2ioh PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ioh ProSAT]</span></td></tr> |
| Diversification of function in the haloacid dehalogenase enzyme superfamily: The role of the cap domain in hydrolytic phosphoruscarbon bond cleavage., Lahiri SD, Zhang G, Dunaway-Mariano D, Allen KN, Bioorg Chem. 2006 Dec;34(6):394-409. Epub 2006 Oct 27. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17070898 17070898]
| | </table> |
| | == Function == |
| | [https://www.uniprot.org/uniprot/PHNX_BACCE PHNX_BACCE] Involved in phosphonate degradation. |
| | == 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/io/2ioh_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/main_output.php?pdb_ID=2ioh ConSurf]. |
| | <div style="clear:both"></div> |
| | __TOC__ |
| | </StructureSection> |
| [[Category: Bacillus cereus]] | | [[Category: Bacillus cereus]] |
| [[Category: Single protein]] | | [[Category: Large Structures]] |
| [[Category: Allen, K.A.]] | | [[Category: Allen KA]] |
| [[Category: Dunaway-Mariano, D.]] | | [[Category: Dunaway-Mariano D]] |
| [[Category: Lahiri, S.D.]] | | [[Category: Lahiri SD]] |
| [[Category: Peisach, E.]] | | [[Category: Peisach E]] |
| [[Category: Zhang, G.]] | | [[Category: Zhang G]] |
| [[Category: MG]]
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| [[Category: PO4]]
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| [[Category: haloacid dehalogenase superfamily]]
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| [[Category: phosphonoacetaldehyde hydrolase]]
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| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 14:16:18 2008''
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