title: Activation of 11R-lipoxygenase is fully Ca(2+)-dependent and controlled by the phospholipid composition of the target membrane.
abstract: Activation of some lipoxygenases (LOX) is found to be related to the selective membrane binding upon cell stimulation. In this study, a systematic analysis of the effect of the lipid composition on the membrane binding efficiency, Ca(2+) affinity, and enzymatic activity of 11R-LOX was performed. The analysis of the membrane targeting by fluorometric and surface plasmon resonance measurements in the absence of Ca(2+) showed an exclusive binding of 11R-LOX to the anionic phospholipids (phosphatidylinositol < phosphatidylglycerol ≈ phosphatidylserine) containing model membranes. The presence of Ca(2+) enhanced the rate of interaction and influenced its mode. The modulation of the activity of 11R-LOX indicated that (i) Ca(2+) binding is a prerequisite for productive membrane association, (ii) the reaction of 11R-LOX with arachidonic acid coincided with and was driven by its Ca(2+)-mediated membrane association, and (iii) phosphatidylethanolamine and anionic phospholipids had a synergistic effect on the Ca(2+) affinity, in line with a target-activated messenger affinity mechanism [Corbin, J. A., et al. (2007) Biochemistry 46, 4322-4336]. According to the mechanism proposed in this report, 11R-LOX can bind to the membranes in two different modes and the efficiency of productive membrane binding is determined by a concerted association of Ca(2+) and lipid headgroups.
authors.affiliation: Department of Chemistry, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
authors.forename: Reet
authors.initials: R
authors.lastname: Järving
authors.forename: Aivar
authors.initials: A
authors.lastname: Lõokene
authors.forename: Reet
authors.initials: R
authors.lastname: Kurg
authors.forename: Liina
authors.initials: L
authors.lastname: Siimon
authors.forename: Ivar
authors.initials: I
authors.lastname: Järving
authors.forename: Nigulas
authors.initials: N
authors.lastname: Samel
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008084:Lipoxygenase / Q000737:chemistry* / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance
chemical_list: D010743:Phospholipids; D008084:Lipoxygenase; D002118:Calcium