title: Biochemical characterization of proline dehydrogenase in Arabidopsis mitochondria.
abstract: Proline has multiple functions in plants. Besides being a building block for protein biosynthesis proline plays a central role in the plant stress response and in further cellular processes. Here, we report an analysis on the integration of proline dehydrogenase (ProDH) into mitochondrial metabolism in Arabidopsis thaliana. An experimental system to induce ProDH activity was established using cell cultures. Induction of ProDH was measured by novel photometric activity assays and by a ProDH in gel activity assay. Effects of increased ProDH activity on other mitochondrial enzymes were systematically investigated. Activities of the protein complexes of the respiratory chain were not significantly altered. In contrast, some mitochondrial dehydrogenases had markedly changed activities. Activity of glutamate dehydrogenase substantially increased, indicating upregulation of the entire proline catabolic pathway, which was confirmed by co-expression analyses of the corresponding genes. Furthermore, activity of d-lactate dehydrogenase was increased. d-lactate was identified to be a competitive inhibitor of ProDH in plants. We suggest that induction of d-lactate dehydrogenase activity allows rapid upregulation of ProDH activity during the short-term stress response in plants.
authors.affiliation: Institute of Plant Genetics, Plant Proteomics, Leibniz University Hannover, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schertl
authors.forename: Cécile
authors.initials: C
authors.lastname: Cabassa
authors.forename: Kaouthar
authors.initials: K
authors.lastname: Saadallah
authors.forename: Marianne
authors.initials: M
authors.lastname: Bordenave
authors.forename: Arnould
authors.initials: A
authors.lastname: Savouré
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Braun
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D015153:Blotting, Western; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology*; D011394:Proline Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013237:Stereoisomerism; D015854:Up-Regulation
chemical_list: D019344:Lactic Acid; D005969:Glutamate Dehydrogenase; D011394:Proline Oxidase
keywords: At3g30775; dehydrogenase; enzyme inhibitor; mitochondria; plant; proline; proline dehydrogenase (ProDH); stress response