Claus Schneider
Last active: 4/5/2016

Control of prostaglandin stereochemistry at the 15-carbon by cyclooxygenases-1 and -2. A critical role for serine 530 and valine 349.

Schneider C, Boeglin WE, Prusakiewicz JJ, Rowlinson SW, Marnett LJ, Samel N, Brash AR
J Biol Chem. 2002 277 (1): 478-85

PMID: 11677234 · DOI:10.1074/jbc.M107471200

Prostaglandin synthesis by cyclooxygenases-1 and -2 (COX-1 and COX-2) involves an initial oxygenation of arachidonic acid at C-11, followed by endoperoxide and cyclopentane ring formation, and then a second reaction with molecular oxygen in the S configuration at C-15. The resulting 15S-hydroxyl group of prostaglandins is crucial for their bioactivity. Using human COX-1 and human and murine COX-2, we have identified two amino acids located in the oxygenase active site that control the stereochemistry at C-15. The most crucial determinant is Ser-530, the residue that is acetylated by aspirin. In COX-2, site-directed mutagenesis of Ser-530 to methionine, threonine, or valine produced highly active enzymes that formed 82-95% 15R-configuration prostaglandins; these have the opposite stereochemistry at C-15 to the natural products. In COX-1, the corresponding Ser-530 mutations inactivated the enzyme. The second residue, Val-349, exerts a more subtle influence. When Val-349 was replaced by isoleucine, the mutant COX-1 and COX-2 enzymes formed 41 and 65% 15R-prostaglandins, respectively. This change was highly specific for isoleucine, as mutations of Val-349 to alanine, leucine, asparagine, or threonine did not alter or only slightly altered (< or =13%) the S-configuration at C-15. These results establish a previously unrecognized role for Ser-530 and Val-349 in maintaining the correct S stereochemistry of the carbon-15 hydroxyl group during prostaglandin synthesis. The findings may also explain the absolute conservation of Ser-530, the target of aspirin, throughout the families of cyclooxygenase enzymes.

MeSH Terms (13)

Animals Cyclooxygenase 1 Cyclooxygenase 2 Humans Hydroxyeicosatetraenoic Acids Isoenzymes Membrane Proteins Mice Molecular Conformation Mutagenesis, Site-Directed Prostaglandin-Endoperoxide Synthases Prostaglandins Serine

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