Uncovering a calcium-regulated membrane-binding mechanism for soybean lipoxygenase-1

Suren A. Tatulian, Janusz Steczko, Wladek Minor

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Lipoxygenases catalyze the biosynthesis of leukotrienes, lipoxins, and other lipid-derived mediators that are involved in a wide variety of pathophysiological processes, including inflammation, allergy, and tumorigenesis. Mammalian lipoxygenases are activated by a calcium-mediated translocation to intracellular membranes upon cell stimulation, and cooperate with cytosolic phospholipase A2 at the membrane surface to generate eicosanoids. Although it has been documented that plant cell stimulation increases intracellular Ca2+ concentration and activates cytosolic phospholipase A2, followed by lipoxygenase-catalyzed conversion of the liberated linolenic acid to jasmonic acid, no evidence is available for Ca2+-regulated membrane binding and activity of plant lipoxygenases. Plant lipoxygenases, unlike their mammalian counterparts, are believed to function independently of calcium or membranes. Here we present spectroscopic evidence for a calcium-regulated membrane-binding mechanism of soybean lipoxygenase-1 (L-1). Both calcium and membrane binding affect the structure and the mode of action of L-1. Free L-1 in solution is less accessible to the polar solvent and converts linoleic acid to conjugated dienes, whereas surface binding increases solvent accessibility and stimulates conjugated ketodiene production. Calcium exerts a biphasic effect on the structure and activity of L-1. Our results uncover a new regulatory mechanism for plant lipoxygenases and delineate common features in animal and plant cell signaling pathways.

Original languageEnglish
Pages (from-to)15481-15490
Number of pages10
JournalBiochemistry
Volume37
Issue number44
DOIs
StatePublished - 3 Nov 1998
Externally publishedYes

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