1dci
From Proteopedia
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'''DIENOYL-COA ISOMERASE''' | '''DIENOYL-COA ISOMERASE''' | ||
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[[Category: Novikov, D.]] | [[Category: Novikov, D.]] | ||
[[Category: Wierenga, R K.]] | [[Category: Wierenga, R K.]] | ||
| - | [[Category: | + | [[Category: Dienoyl-coa isomerase]] |
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| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 13:41:28 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 10:41, 2 May 2008
DIENOYL-COA ISOMERASE
Overview
BACKGROUND: The degradation of unsaturated fatty acids is vital to all living organisms. Certain unsaturated fatty acids must be catabolized via a pathway auxiliary to the main beta-oxidation pathway. Dienoyl-coenzyme A (dienoyl-CoA) isomerase catalyzes one step of this auxiliary pathway, the isomerization of 3-trans,5-cis-dienoyl-CoA to 2-trans,4-trans-dienoyl-CoA, and is imported into both mitochondria and peroxisomes. Dienoyl-CoA isomerase belongs to a family of CoA-binding proteins that share the enoyl-CoA hydratase/isomerase sequence motif. RESULTS: The crystal structure of rat dienoyl-CoA isomerase has been determined at 1.5 A resolution. The fold closely resembles that of enoyl-CoA hydratase and 4-chlorobenzoyl-CoA dehalogenase. Dienoyl-CoA isomerase forms hexamers made up of two trimers. The structure contains a well ordered peroxisomal targeting signal type-1 which is mostly buried in the inter-trimer space. The active-site pocket is deeply buried and entirely hydrophobic, with the exception of the acidic residues Asp176, Glu196 and Asp204. Site-directed mutagenesis of Asp204 revealed that this residue is essential for catalysis. In a molecular modeling simulation, a molecule of 3-trans,5-cis-octadienoyl-CoA was docked into the active site. CONCLUSIONS: The structural data, supported by the mutagenesis data, suggest a reaction mechanism where Glu196 acts as a proton acceptor and Asp204 acts as a proton donor. Asp176 is paired with Glu196 and is important for optimizing the catalytic proton transfer properties of Glu196. In the predicted mode of substrate binding, an oxyanion hole stabilizes the transition state by binding the thioester oxygen. The presence of a buried peroxisomal targeting signal suggests that dienoyl-CoA isomerase is prevented from reaching its hexameric structure in the cytosol.
About this Structure
1DCI is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
The crystal structure of dienoyl-CoA isomerase at 1.5 A resolution reveals the importance of aspartate and glutamate sidechains for catalysis., Modis Y, Filppula SA, Novikov DK, Norledge B, Hiltunen JK, Wierenga RK, Structure. 1998 Aug 15;6(8):957-70. PMID:9739087 Page seeded by OCA on Fri May 2 13:41:28 2008
