View source for 6jcz


==Cryo-EM Structure of Sulfolobus solfataricus ketol-acid reductoisomerase (Sso-KARI) in complex with Mg2+, NADPH, and CPD at pH7.5==
<SX load='6jcz' size='340' side='right' viewer='molstar' caption='[[6jcz]], [[Resolution|resolution]] 3.35&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6jcz]] is a 12 chain structure with sequence from [http://en.wikipedia.org/wiki/Sacs2 Sacs2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6JCZ OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=6JCZ FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=9TY:cyclopropane-1,1-dicarboxylic+acid'>9TY</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NDP:NADPH+DIHYDRO-NICOTINAMIDE-ADENINE-DINUCLEOTIDE+PHOSPHATE'>NDP</scene></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">ilvC2, ilvC-2, SSO1322 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=273057 SACS2])</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Ketol-acid_reductoisomerase Ketol-acid reductoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.86 1.1.1.86] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=6jcz FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6jcz OCA], [http://pdbe.org/6jcz PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6jcz RCSB], [http://www.ebi.ac.uk/pdbsum/6jcz PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6jcz ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
While cryo-EM is revolutionizing structural biology, its impact on enzymology is yet to be fully demonstrated. The ketol-acid reductoisomerase (KARI) catalyzes conversion of (2 S)-acetolactate or (2 S)-aceto-2-hydroxybutyrate to 2,3-dihydroxy-3-alkylbutyrate. We found that KARI from archaea Sulfolobus solfataricus (Sso-KARI) is unusual in being a dodecamer, bispecific to NADH and NADPH, and losing activity above pH 7.8. While crystals were obtainable only at pH 8.5, cryo-EM structures were solved at pH 7.5 and 8.5 for Sso-KARI:2Mg(2+). The results showed that the distances of the two catalytic Mg(2+) ions are lengthened in both structures at pH 8.5. We next solved cryo-EM structures of two Sso-KARI complexes, with NADH+inhibitor and NADPH+inhibitor at pH 7.5, which indicate that the bispecificity can be attributed to a unique asparagine at the cofactor binding loop. Unexpectedly, Sso-KARI also differs from other KARI enzymes in lacking "induced-fit", reflecting structural rigidity. Thus, cryo-EM is powerful for structural and mechanistic enzymology.

Use of Cryo-EM To Uncover Structural Bases of pH Effect and Cofactor Bispecificity of Ketol-Acid Reductoisomerase.,Chen CY, Chang YC, Lin BL, Lin KF, Huang CH, Hsieh DL, Ko TP, Tsai MD J Am Chem Soc. 2019 Apr 2. doi: 10.1021/jacs.9b01354. PMID:30921515<ref>PMID:30921515</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 6jcz" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
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[[Category: Ketol-acid reductoisomerase]]
[[Category: Large Structures]]
[[Category: Sacs2]]
[[Category: Chang, Y C]]
[[Category: Chen, C Y]]
[[Category: Hsieh, D L]]
[[Category: Huang, C H]]
[[Category: Ko, T P]]
[[Category: Lin, B L]]
[[Category: Lin, K F]]
[[Category: Tsai, M D]]
[[Category: Bi-specific]]
[[Category: Dodecamer]]
[[Category: Isomerase]]
[[Category: Knotted protein]]
[[Category: Magnesium-dependent]]
[[Category: Reductoisomerase]]
[[Category: Thermostable]]