4rut
From Proteopedia
crystal structure of murine cyclooxygenase-2 with 13-methyl-arachidonic Acid
Structural highlights
Function[PGH2_MOUSE] Mediates the formation of prostaglandins from arachidonate. May have a role as a major mediator of inflammation and/or a role for prostanoid signaling in activity-dependent plasticity.[1] [2] [3] [4] Publication Abstract from PubMedCyclooxygenase-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. 13-methylarachidonic Acid is a positive allosteric modulator of endocannabinoid oxygenation by cyclooxygenase.,Kudalkar SN, Nikas SP, Kingsley PJ, Xu S, Galligan JJ, Rouzer CA, Banerjee S, Ji L, Eno MR, Makriyannis A, Marnett LJ J Biol Chem. 2015 Mar 20;290(12):7897-909. doi: 10.1074/jbc.M114.634014. Epub, 2015 Feb 2. PMID:25648895[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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