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Plant dihydroorotate dehydrogenase differs significantly in substrate specificity and inhibition from the animal
Alexandra Ullrich1, Wolfgang Knecht, Jure Piskur
1Institute for Physiological Chemistry, Philipps-University, Karl-von-Frisch-Strasse 1, D-35033 Marburg, Germany. ullricha@mailer.uni-marburg.de
Abstract:
The mitochondrial membrane bound dihydroorotate dehydrogenase (DHODH; EC 1.3.99.11) catalyzes the fourth step of pyrimidine biosynthesis. By the present correction of a known cDNA sequence for Arabidopsis thaliana DHODH we revealed the importance of the very C-terminal part for its catalytic activity and the reason why--in contrast to mammalian and insect species--the recombinant plant flavoenzyme was unaccessible to date for in vitro characterization. Structure-activity relationship studies explained that potent inhibitors of animal DHODH do not significantly affect the plant enzyme. These difference could be exploited for a novel approach to herb or pest growth control by limitation of pyrimidine nucleotide pools.