4E1G

X-ray crystal structure of alpha-linolenic acid bound to the cyclooxygenase channel of cyclooxygenase-2

Summary for 4E1G

• Entry DOI: 10.2210/pdb4e1g/pdb
• Related: 1DIY 3HS5 3HS6 3HS7 3QH0 3TZI
• Descriptor: Prostaglandin G/H synthase 2, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (10 entities in total)
• Functional Keywords: monotopic membrane protein, biological dimer, oxidoreductase, cox-2, n-glycosylation, membrane of er
• Biological source: Mus musculus (mouse)
• Total number of polymer chains: 2
• Total formula weight: 144726.69

Authors

Vecchio, A.J.,Malkowski, M.G. (deposition date: 2012-03-06, release date: 2012-04-25, Last modification date: 2024-11-27)

Primary citation

Vecchio, A.J.,Orlando, B.J.,Nandagiri, R.,Malkowski, M.G.
Investigating Substrate Promiscuity in Cyclooxygenase-2: THE ROLE OF ARG-120 AND RESIDUES LINING THE HYDROPHOBIC GROOVE.
J.Biol.Chem., 287:24619-24630, 2012

PubMed Abstract: The cyclooxygenases (COX-1 and COX-2) generate prostaglandin H(2) from arachidonic acid (AA). In its catalytically productive conformation, AA binds within the cyclooxygenase channel with its carboxylate near Arg-120 and Tyr-355 and ω-end located within a hydrophobic groove above Ser-530. Although AA is the preferred substrate for both isoforms, COX-2 can oxygenate a broad spectrum of substrates. Mutational analyses have established that an interaction of the carboxylate of AA with Arg-120 is required for high affinity binding by COX-1 but not COX-2, suggesting that hydrophobic interactions between the ω-end of substrates and cyclooxygenase channel residues play a significant role in COX-2-mediated oxygenation. We used structure-function analyses to investigate the role that Arg-120 and residues lining the hydrophobic groove play in the binding and oxygenation of substrates by murine (mu) COX-2. Mutations to individual amino acids within the hydrophobic groove exhibited decreased rates of oxygenation toward AA with little effect on binding. R120A muCOX-2 oxygenated 18-carbon ω-6 and ω-3 substrates albeit at reduced rates, indicating that an interaction with Arg-120 is not required for catalysis. Structural determinations of Co(3+)-protoporphyrin IX-reconstituted muCOX-2 with α-linolenic acid and G533V muCOX-2 with AA indicate that proper bisallylic carbon alignment is the major determinant for efficient substrate oxygenation by COX-2. Overall, these findings implicate Arg-120 and hydrophobic groove residues as determinants that govern proper alignment of the bisallylic carbon below Tyr-385 for catalysis in COX-2 and confirm nuances between COX isoforms that explain substrate promiscuity.

PubMed: 22637474
DOI: 10.1074/jbc.M112.372243

Experimental method

X-RAY DIFFRACTION (2.1 Å)