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| [[Image:1grp.jpg|left|200px]]
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| <!-- | | ==REGULATORY AND CATALYTIC MECHANISMS IN ESCHERICHIA COLI ISOCITRATE DEHYDROGENASE: MULTIPLE ROLES FOR N115== |
| The line below this paragraph, containing "STRUCTURE_1grp", creates the "Structure Box" on the page.
| | <StructureSection load='1grp' size='340' side='right'caption='[[1grp]], [[Resolution|resolution]] 2.50Å' scene=''> |
| You may change the PDB parameter (which sets the PDB file loaded into the applet) | | == Structural highlights == |
| or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
| | <table><tr><td colspan='2'>[[1grp]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GRP OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1GRP FirstGlance]. <br> |
| or leave the SCENE parameter empty for the default display.
| | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5Å</td></tr> |
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| | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ICT:ISOCITRIC+ACID'>ICT</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr> |
| {{STRUCTURE_1grp| PDB=1grp | SCENE= }}
| | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1grp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1grp OCA], [https://pdbe.org/1grp PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1grp RCSB], [https://www.ebi.ac.uk/pdbsum/1grp PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1grp ProSAT]</span></td></tr> |
| | </table> |
| | == Function == |
| | [https://www.uniprot.org/uniprot/IDH_ECOLI IDH_ECOLI] |
| | == 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/gr/1grp_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=1grp ConSurf]. |
| | <div style="clear:both"></div> |
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| '''REGULATORY AND CATALYTIC MECHANISMS IN ESCHERICHIA COLI ISOCITRATE DEHYDROGENASE: MULTIPLE ROLES FOR N115'''
| | ==See Also== |
| | | *[[Isocitrate dehydrogenase 3D structures|Isocitrate dehydrogenase 3D structures]] |
| | | __TOC__ |
| ==Overview== | | </StructureSection> |
| Inactivation of Escherichia coli isocitrate dehydrogenase upon phosphorylation at S113 depends upon the direct electrostatic repulsion of the negatively charged gamma-carboxylate of isocitrate by the negatively charged phosphoserine. The effect is mimicked by replacing S113 with aspartate or glutamate, which reduce performance (kcat/K(i).isocitrat/ Km.NADP) by a factor of 10(7). Here, we demonstrate that the inactivating effects of the electrostatic repulsion are completely eliminated by a second-site mutation, and provide the structural basis for this striking example of intragenic suppression. N115 is adjacent to S113 on one face of the D-helix, interacts with isocitrate and NADP+, and has been postulated to serve in both substrate binding and in catalysis. The single N115L substitution reduces affinity for isocitrate by a factor of 50 and performance by a factor of 500. However, the N115L substitution completely suppresses the inactivating electrostatic effects of S113D or S113E: the performance of the double mutants is 10(5) higher than the S113D and S113E single mutants. These mutations have little effect on the kinetics of alternative substrates, which lack the charged gamma-carboxylate of isocitrate. Both glutamate and aspartate at site 113 remain fully ionized in the presence of leucine. In the crystal structure of the N115L mutant, the leucine adopts a different conformer from the wild-type asparagine. Repacking around the leucine forces the amino-terminus of the D-helix away from the rest of the active site. The hydrogen bond between E113 and N115 in the S113E single mutant is broken in the S113E/N115L mutant, allowing the glutamate side chain to move away from the gamma-carboxylate of isocitrate. These movements increase the distance between the carboxylates, diminish the electrostatic repulsion, and lead to the remarkably high activity of the S113E/N115L mutant.
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| ==About this Structure==
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| 1GRP is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GRP OCA].
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| ==Reference==
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| Second-site suppression of regulatory phosphorylation in Escherichia coli isocitrate dehydrogenase., Chen R, Grobler JA, Hurley JH, Dean AM, Protein Sci. 1996 Feb;5(2):287-95. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8745407 8745407]
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| [[Category: Escherichia coli]] | | [[Category: Escherichia coli]] |
| [[Category: Single protein]] | | [[Category: Large Structures]] |
| [[Category: Grobler, J A.]] | | [[Category: Grobler JA]] |
| [[Category: Hurley, J H.]] | | [[Category: Hurley JH]] |
| [[Category: Glyoxylate bypass]]
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| [[Category: Nadp]]
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| [[Category: Oxidoreductase]]
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| [[Category: Phosphorylation]]
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| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:55:49 2008''
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