An oxygenase inhibitor study in Solanum lycopersicum combined with metabolite profiling analysis revealed a potent peroxygenase inactivator.
Plant genomes contain a vast number of oxygenase genes, but only very few have been functionally characterized. To devise an alternative method for the detection of novel oxygenase-catalysed reactions the effects of the cytochrome P450 oxygenase inhibitors 1-aminobenzotriazole (ABT) and tetcyclacis (TET) have been examined by metabolite profiling analysis in tomato fruit (Solanum lycopersicum). Treatment with TET resulted in significant increases in the levels of certain flavonoids, whereas ABT strongly inhibited their formation during fruit ripening. Injections of buffered solutions of ABT into tomato fruits led rather to an accumulation of 9,12,13-trihydroxy-10(E)-octadecenoic acid probably due to retarded metabolism of the hydroxylated acid, while TET completely repressed its formation. Peroxygenase, a hydroperoxide-dependent hydroxylase involved in the formation of the trihydroxy fatty acid, is strongly inhibited by TET (IC(50) 2.6 μM) as was demonstrated by studies with the recombinant tomato enzyme expressed in yeast. The data show that ABT and TET affect oxygenases differently in tomato fruit and reveal that these enzymes catalyse distinct reactions in different metabolic pathways, among which C(18)-trihydroxy fatty acid and flavonoid metabolism involve novel oxygenase-catalysed reactions. The method is suitable to identify potential substrates and products of ripening-related, putative oxygenases and can support functional analyses of recombinant enzymes.
Department of Plant Biology, Faculty of Sciences, University of Dschang, PO Box 67, Dschang, Cameroon.
Jean
J
Aghofack-Nguemezi
Christopher
C
Fuchs
Su-Ying
SY
Yeh
Fong-Chin
FC
Huang
Thomas
T
Hoffmann
Wilfried
W
Schwab
D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000378:metabolism; D005638:Fruit / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D055442:Metabolome / Q000187:drug effects; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005419:Flavonoids; D010940:Plant Proteins; D014230:Triazoles; C033020:1-aminobenzotriazole; C053723:tetcyclacis; D006899:Mixed Function Oxygenases; C022333:peroxygenase