|
|
| (15 intermediate revisions by the same user not shown) |
| Line 1: |
Line 1: |
| [[Image:1fq0.jpg|left|200px]]<br /><applet load="1fq0" size="350" color="white" frame="true" align="right" spinBox="true"
| |
| caption="1fq0, resolution 2.10Å" />
| |
| '''KDPG ALDOLASE FROM ESCHERICHIA COLI'''<br />
| |
|
| |
|
| ==Overview== | | ==KDPG ALDOLASE FROM ESCHERICHIA COLI== |
| BACKGROUND: Aldolases are carbon bond-forming enzymes that have long been identified as useful tools for the organic chemist. However, their utility is limited in part by their narrow substrate utilization. Site-directed mutagenesis of various enzymes to alter their specificity has been performed for many years, typically without the desired effect. More recently directed evolution has been employed to engineer new activities onto existing scaffoldings. This approach allows random mutation of the gene and then selects for fitness to purpose those proteins with the desired activity. To date such approaches have furnished novel activities through multiple mutations of residues involved in recognition; in no instance has a key catalytic residue been altered while activity is retained. RESULTS: We report a double mutant of E. coli 2-keto-3-deoxy-6-phosphogluconate aldolase with reduced but measurable enzyme activity and a synthetically useful substrate profile. The mutant was identified from directed-evolution experiments. Modification of substrate specificity is achieved by altering the position of the active site lysine from one beta strand to a neighboring strand rather than by modification of the substrate recognition site. The new enzyme is different to all other existing aldolases with respect to the location of its active site to secondary structure. The new enzyme still displays enantiofacial discrimination during aldol addition. We have determined the crystal structure of the wild-type enzyme (by multiple wavelength methods) to 2.17 A and the double mutant enzyme to 2.7 A resolution. CONCLUSIONS: These results suggest that the scope of directed evolution is substantially larger than previously envisioned in that it is possible to perturb the active site residues themselves as well as surrounding loops to alter specificity. The structure of the double mutant shows how catalytic competency is maintained despite spatial reorganization of the active site with respect to substrate.
| | <StructureSection load='1fq0' size='340' side='right'caption='[[1fq0]], [[Resolution|resolution]] 2.10Å' scene=''> |
| | == Structural highlights == |
| | <table><tr><td colspan='2'>[[1fq0]] is a 3 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=1FQ0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1FQ0 FirstGlance]. <br> |
| | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.1Å</td></tr> |
| | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CIT:CITRIC+ACID'>CIT</scene></td></tr> |
| | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1fq0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1fq0 OCA], [https://pdbe.org/1fq0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1fq0 RCSB], [https://www.ebi.ac.uk/pdbsum/1fq0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1fq0 ProSAT]</span></td></tr> |
| | </table> |
| | == Function == |
| | [https://www.uniprot.org/uniprot/ALKH_ECOLI ALKH_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/fq/1fq0_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=1fq0 ConSurf]. |
| | <div style="clear:both"></div> |
|
| |
|
| ==About this Structure== | | ==See Also== |
| 1FQ0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=CIT:'>CIT</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/2-dehydro-3-deoxy-phosphogluconate_aldolase 2-dehydro-3-deoxy-phosphogluconate aldolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.2.14 4.1.2.14] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FQ0 OCA].
| | *[[Aldolase 3D structures|Aldolase 3D structures]] |
| | | __TOC__ |
| ==Reference==
| | </StructureSection> |
| Directed evolution of a new catalytic site in 2-keto-3-deoxy-6-phosphogluconate aldolase from Escherichia coli., Wymer N, Buchanan LV, Henderson D, Mehta N, Botting CH, Pocivavsek L, Fierke CA, Toone EJ, Naismith JH, Structure. 2001 Jan 10;9(1):1-9. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11342129 11342129]
| |
| [[Category: 2-dehydro-3-deoxy-phosphogluconate aldolase]]
| |
| [[Category: Escherichia coli]] | | [[Category: Escherichia coli]] |
| [[Category: Single protein]] | | [[Category: Large Structures]] |
| [[Category: Naismith, J H.]] | | [[Category: Naismith JH]] |
| [[Category: CIT]]
| |
| [[Category: aldolase]]
| |
| [[Category: tim barrel]]
| |
| | |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:41:29 2008''
| |
