Molecular and biochemical analysis of the novel molybdenum-enzyme mARC

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In this project we want to unveil the function and importance of plant mARC-like proteins, of which two are encoded by the genome of Arabidopsis thaliana. mARC (mitochondrial amidoxime reducing component) is a novel molybdenum-enzyme that we have very recently discovered in mammals. Our preliminary work showed that mARC from the outer membrane of pig liver mitochondria is the smallest molybdenum-enyzme known in eukaryotes and that its activity is strictly dependent on molybdenum cofactor. mARC seems to represent a new type of molybdenum-proteins as it gains enzymatic activity only in complex with other proteins, while all other molybdenum-enzymes known to date comprise all prosthetic groups required for activity within a single polypetide chain. We will study the enzymatic and structural characteristics of plant mARC-like proteins and examine whether these proteins are associated with other proteins forming a redox complex. We intend to analyze whether the plant mARC homologs are located at the outer membrane of mitochondria and whether they have N-reducing capacity. Finally we want to delineate the metabolic role played by mARC-like proteins and clarify their importance for the plant.