6OFY

Crystal Structure of Arachidonic Acid bound to V349I murine COX-2

Summary for 6OFY

• Entry DOI: 10.2210/pdb6ofy/pdb
• Descriptor: Prostaglandin G/H synthase 2, 2-acetamido-2-deoxy-beta-D-glucopyranose, PROTOPORPHYRIN IX CONTAINING CO, ... (7 entities in total)
• Functional Keywords: arachidonic acid cyclooxygenase prostaglandin endoperoxide synthase, membrane protein, oxidoreductase
• Biological source: Mus musculus (Mouse)
• Total number of polymer chains: 2
• Total formula weight: 131207.35

Authors

Malkowski, M.G. (deposition date: 2019-04-01, release date: 2020-02-05, Last modification date: 2023-10-11)

Primary citation

Dong, L.,Anderson, A.J.,Malkowski, M.G.
Arg-513 and Leu-531 Are Key Residues Governing Time-Dependent Inhibition of Cyclooxygenase-2 by Aspirin and Celebrex.
Biochemistry, 58:3990-4002, 2019

PubMed Abstract: Aspirin and Celebrex are well-known time-dependent inhibitors of the cyclooxygenases (COX). Molecular dynamics simulations suggest that Arg-513 and Leu-531 contribute to the structural mechanisms of COX inhibition. We used mutagenesis and functional analyses to characterize how substitutions at these positions influence time-dependent inhibition by aspirin and Celebrex. We show that substitutions of Leu-531 with asparagine and phenylalanine significantly attenuate time-dependent inhibition of COX-2 by these drugs. The introduction of side chain bulk, rigidity, and charge would disrupt the formation of the initial noncovalent complex, in the case of aspirin, and the "high-affinity" binding state, in the case of Celebrex. Substitution of Arg-513 with histidine (the equivalent residue in COX-1) resulted in a 2-fold potentiation of aspirin inhibition, in support of the hypothesis that the presence of histidine in COX-1 lowers the activation barrier associated with the formation of the initial noncovalent enzyme-inhibitor complex. As a corollary, we previously hypothesized that the flexibility associated with Leu-531 contributes to the binding of arachidonic acid (AA) to acetylated COX-2 to generate 15-hydroxyeicosatetraenoic acid (15R-HETE). We determined the X-ray crystal structure of AA bound to Co-protoporphyrin IX-reconstituted V349I murine COX-2 (muCOX-2). V349I muCOX-2 was utilized as a surrogate to trap AA in a conformation leading to 15R-HETE. AA binds in a C-shaped pose, facilitated by the rotation of the Leu-531 side chain. Ile-349 is positioned to sterically shield antarafacial oxygen addition at carbon-15 in a manner similar to that proposed for the acetylated Ser-530 side chain.

PubMed: 31469551
DOI: 10.1021/acs.biochem.9b00659

Experimental method

X-RAY DIFFRACTION (2.2 Å)