Gene Deletion of 7,8-Linoleate Diol Synthase of the Rice Blast Fungus

• DOI: 10.1074/jbc.m109.062810
• Publication Date: 2009-12-21T01:12:46Z
• Authors: Fredrik Jernerén; Ane Sesma; Marina Franchesch...; Mats Hamberg; Ernst H. Oliw
• Keywords: Appressorium

Linoleate diol synthases (LDS) are heme enzymes, which oxygenate 18:2n-6 sequentially to (8R)-hydroperoxylinoleic acid ((8R)-HPODE) and (5S,8R)-dihydroxy-, (7S,8S)-dihydroxy-, or (8R,11S)-dihydroxylinoleic acids (DiHODE). The genome of the rice blast fungus, Magnaporthe oryzae, contains two genes with homology LDS. M. oryzae oxidized (8R)-HPODE (7S,8S)-DiHODE, (6S,8R)-DiHODE, (8R,11S)-HODE. Small amounts 10-hydroxy-(8E,12Z)-octadecadienoic traces 5,8-DiHODE were also detected by liquid chromatography-mass spectrometry. contribution 7,8-LDS gene pathogenicity was evaluated replacement catalytic domain hygromycin green fluorescent protein variant (SGFP) cassettes. This genetically modified strain Delta7,8-LDS infected leaves roots formed appressoria conidia as native fungus. mutant had lost capacity biosynthesize all metabolites except small 8-hydroxylinoleic acid. Studies stereospecifically deuterated linoleic showed that abstraction pro-S hydrogen at C-8 antarafacial oxygenation, whereas (7S,8S)-DiHODE (8R,11S)-DiHODE from suprafacial oxygenation C-7 C-11, respectively. A mac1 suppressor (Delta sum1-99) shows cAMP-independent kinase activity, oxygenated increased (10R)-HPODE (5S,8R)-DiHODE. Expression but not second homologue in mutant. suggests PKA-mediated signaling pathway regulates dioxygenase hydroperoxide isomerase activities oryzae.