title: Auxins action on Glycine max secretory phospholipase A2 is mediated by the interfacial properties imposed by the phytohormones.
abstract: Secretory phospholipase A2 (sPLA2) are soluble enzymes that catalyze the conversion of phospholipids to lysophospholipids and free fatty acids at membrane interfaces. The effect of IAA and IPA auxins over the activity of recombinant sPLA2 isoforms from Glycine max was studied using membrane model systems including mixed micelles and Langmuir lipid monolayers. Both phytohormones stimulate the activity of both plant sPLA2 using DLPC/Triton mixed micelles as substrate. To elucidate the mechanism of action of the phytohormones, we showed that both auxins are able to self-penetrate lipid monolayers and cause an increment in surface pressure and an expansion of lipid/phytohormone mixed interfaces. The stimulating effect of auxins over phospholipase A2 activity was still present when using Langmuir mixed monolayers as organized substrate regardless of sPLA2 source (plant or animal). All the data suggest that the stimulating effect of auxins over sPLA2 is due to a more favorable interfacial environment rather to a direct effect over the enzyme.
authors.affiliation: Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, UNC, CONICET, Departamento de Química Biológica, Fac. de Cs. Químicas, Universidad Nacional de Córdoba. Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
authors.forename: María Elisa
authors.initials: ME
authors.lastname: Mariani
authors.affiliation: Departamento de Fundamentación Biológica, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Ricardo Román
authors.initials: RR
authors.lastname: Madoery
authors.affiliation: Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, UNC, CONICET, Departamento de Química Biológica, Fac. de Cs. Químicas, Universidad Nacional de Córdoba. Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina. Electronic address: gfidelio@mail.fcq.unc.edu.ar.
authors.forename: Gerardo Daniel
authors.initials: GD
authors.lastname: Fidelio
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008823:Micelles; D054497:Phospholipases A2, Secretory / Q000235:genetics / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013025:Glycine max / Q000187:drug effects* / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D007210:Indoleacetic Acids; D008823:Micelles; D010937:Plant Growth Regulators; D020033:Protein Isoforms; D011994:Recombinant Proteins; D054497:Phospholipases A2, Secretory
keywords: Auxin stimulation; Glycine max phospholipase A(2); Indole-3-acetic acid; Indole-3-propionic acid; Interfacial catalysis; Soybean sPLA(2)s