1i8b

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(New page: 200px<br /><applet load="1i8b" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i8b, resolution 1.95&Aring;" /> '''CHALCONE SYNTHASE (G...)
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[[Image:1i8b.jpg|left|200px]]<br /><applet load="1i8b" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1i8b, resolution 1.95&Aring;" />
 
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'''CHALCONE SYNTHASE (G256F)'''<br />
 
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==Overview==
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==Chalcone synthase (G256F)==
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Chalcone synthase (CHS) belongs to the family of type III polyketide, synthases (PKS) that catalyze formation of structurally diverse, polyketides. CHS synthesizes a tetraketide by sequential condensation of, three acetyl anions derived from malonyl-CoA decarboxylation to a, p-coumaroyl moiety attached to an active site cysteine. Gly256 resides on, the surface of the CHS active site that is in direct contact with the, polyketide chain derived from malonyl-CoA. Thus, position 256 serves as an, ideal target to probe the link between cavity volume and polyketide, chain-length determination in type III PKS. Functional examination of CHS, G256A, G256V, G256L, and G256F mutants reveals altered product profiles, from that of wild-type CHS. With p-coumaroyl-CoA as a starter molecule, the G256A and G256V mutants produce notably more tetraketide lactone., Further restrictions in cavity volume such as that seen in the G256L and, G256F mutants yield increasing levels of the styrylpyrone bis-noryangonin, from a triketide intermediate. X-ray crystallographic structures of the, CHS G256A, G256V, G256L, and G256F mutants establish that these, substitutions reduce the size of the active site cavity without, significant alterations in the conformations of the polypeptide backbones., The side chain volume of position 256 influences both the number of, condensation reactions during polyketide chain extension and the, conformation of the triketide and tetraketide intermediates during the, cyclization reaction. These results viewed in conjunction with the natural, sequence variation of residue 256 suggest that rapid diversification of, product specificity without concomitant loss of substantial catalytic, activity in related CHS-like enzymes can occur by site-specific evolution, of side chain volume at position 256.
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<StructureSection load='1i8b' size='340' side='right'caption='[[1i8b]], [[Resolution|resolution]] 1.95&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1i8b]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Medicago_sativa Medicago sativa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I8B OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1I8B FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.95&#8491;</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=CSD:3-SULFINOALANINE'>CSD</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1i8b FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1i8b OCA], [https://pdbe.org/1i8b PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1i8b RCSB], [https://www.ebi.ac.uk/pdbsum/1i8b PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1i8b ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/CHS2_MEDSA CHS2_MEDSA] The primary product of this enzyme is 4,2',4',6'-tetrahydroxychalcone (also termed naringenin-chalcone or chalcone) which can under specific conditions spontaneously isomerize into naringenin.<ref>PMID:10653632</ref> <ref>PMID:11732902</ref> <ref>PMID:11959984</ref> <ref>PMID:15380179</ref>
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/i8/1i8b_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</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=1i8b ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1I8B is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Medicago_sativa Medicago sativa]. Active as [http://en.wikipedia.org/wiki/Naringenin-chalcone_synthase Naringenin-chalcone synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.74 2.3.1.74] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1I8B OCA].
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*[[Chalcone synthase|Chalcone synthase]]
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== References ==
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==Reference==
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<references/>
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Structure-guided programming of polyketide chain-length determination in chalcone synthase., Jez JM, Bowman ME, Noel JP, Biochemistry. 2001 Dec 11;40(49):14829-38. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11732902 11732902]
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__TOC__
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</StructureSection>
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[[Category: Large Structures]]
[[Category: Medicago sativa]]
[[Category: Medicago sativa]]
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[[Category: Naringenin-chalcone synthase]]
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[[Category: Bowman ME]]
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[[Category: Single protein]]
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[[Category: Jez JM]]
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[[Category: Bowman, M.E.]]
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[[Category: Noel JP]]
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[[Category: Jez, J.M.]]
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[[Category: Noel, J.P.]]
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[[Category: chalcone synthase]]
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[[Category: polyketide synthase]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 17:09:06 2007''
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Current revision

Chalcone synthase (G256F)

PDB ID 1i8b

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