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13-Methylarachidonic Acid Is a Positive Allosteric Modulator of Endocannabinoid Oxygenation by Cyclooxygenase
- Source :
- Journal of Biological Chemistry. 290:7897-7909
- Publication Year :
- 2015
- Publisher :
- Elsevier BV, 2015.
-
Abstract
- Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid (AA) and the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonylethanolamide to prostaglandins, prostaglandin glyceryl esters, and prostaglandin ethanolamides, respectively. A structural homodimer, COX-2 acts as a conformational heterodimer with a catalytic and an allosteric monomer. Prior studies have demonstrated substrate-selective negative allosteric regulation of 2-AG oxygenation. Here we describe AM-8138 (13(S)-methylarachidonic acid), a substrate-selective allosteric potentiator that augments 2-AG oxygenation by up to 3.5-fold with no effect on AA oxygenation. In the crystal structure of an AM-8138·COX-2 complex, AM-8138 adopts a conformation similar to the unproductive conformation of AA in the substrate binding site. Kinetic analysis suggests that binding of AM-8138 to the allosteric monomer of COX-2 increases 2-AG oxygenation by increasing kcat and preventing inhibitory binding of 2-AG. AM-8138 restored the activity of COX-2 mutants that exhibited very poor 2-AG oxygenating activity and increased the activity of COX-1 toward 2-AG. Competition of AM-8138 for the allosteric site prevented the inhibition of COX-2-dependent 2-AG oxygenation by substrate-selective inhibitors and blocked the inhibition of AA or 2-AG oxygenation by nonselective time-dependent inhibitors. AM-8138 selectively enhanced 2-AG oxygenation in intact RAW264.7 macrophage-like cells. Thus, AM-8138 is an important new tool compound for the exploration of allosteric modulation of COX enzymes and their role in endocannabinoid metabolism.
- Subjects :
- chemistry.chemical_classification
Allosteric modulator
Chemistry
Allosteric regulation
Prostaglandin
Arachidonic Acids
Cell Biology
Lipids
Biochemistry
Endocannabinoid system
Oxygen
Kinetics
chemistry.chemical_compound
Enzyme
Allosteric Regulation
Prostaglandin-Endoperoxide Synthases
Arachidonic acid
Enzyme kinetics
Binding site
Molecular Biology
Endocannabinoids
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 290
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....31780fca549c8b0d079e5bf2e8ff29a0