Characterisation of recombinant Hevea brasiliensis allene oxide synthase : effects of cycloxygenase inhibitors, lipoxygenase inhibitors and salicylates on enzyme activity

Norton Gareth J., Pappusamy Arokiaraj, Yusof Faridah, Pujade-Renaud Valérie, Perkins Mark, Griffiths David, Jones Heddwyn. 2007. Characterisation of recombinant Hevea brasiliensis allene oxide synthase : effects of cycloxygenase inhibitors, lipoxygenase inhibitors and salicylates on enzyme activity. Plant Physiology and Biochemistry, 45 : 129-138.

Résumé : Mechanical wounding and jasmonic acid (JA) treatment have been shown to be important factors in controlling laticifer differentiation in Hevea brasiliensis (rubber tree). With the long-term aim of potentially modifying the endogenous levels of JA in H. brasiliensis by gene transfer, we describe in this paper the molecular cloning of a H. brasiliensis aliene oxide synthase (AOS) cDNA and biochemical characterisation of the recombinant AOS (His6-HbAOS) enzyme. The AOS cDNA encodes a protein with the expected motifs present in CYP74A sub-group of the cytochrome P450 super-family of enzymes that metabolise 13-hydroperoxylinolenic acid (13-HPOT), the intermediate involved in JA synthesis. The recombinant H. brasiliensis AOS enzyme was estimated to have a high binding affinity for 13-HPOT with a K. value of 4.02 ± 0.64 ttM. Consistent with previous studies, mammalian cycloxygenase (COX) and lipoxygenase (LOX) inhibitors were shown to significantly reduce His6-HbAOS enzyme activity. Although JA had no effect on His6-HbAOS, salicylic acid (SA) was shown to significantly inhibit the recombinant AOS enzyme activity in a dose dependent manner. Moreover, it was demonstrated that SA, and various analogues of SA, acted as competitive inhibitors of His6-HbAOS when 13-HPOT was used as substrate. We speculate that this effect of salicylates on AOS activity may be important in cross-talking between the SA and JA signalling pathways in plants during biotic/abiotic stress. © 2007 Elsevier Masson SAS. All rights reserved.

Mots-clés Agrovoc : Hevea brasiliensis, ligase, acide jasmonique, latex, activité enzymatique, génie génétique, laticifère

Mots-clés complémentaires : Synthétase

Classification Agris : F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

• Norton Gareth J., University of Hertfordshire (GBR)
• Pappusamy Arokiaraj, MRB (MYS)
• Yusof Faridah, Universiti Islam Antarabangsa Malaysia (MYS)
• Pujade-Renaud Valérie, CIRAD-AMIS-UMR PIA (FRA)
• Perkins Mark, TARRC (GBR)
• Griffiths David, University of Hertfordshire (GBR)
• Jones Heddwyn, University of Hertfordshire (GBR)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/537780/)

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