Defining the Catalytic Mechanism of Cytokinin Oxidase/Dehydrogenase Reactions

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

This award supports an international collaborative research project between the University of Missouri and the Palacky University Olomouc, Czech Republic that focuses on aspects of plant physiology related to the enzymology of cytokinin oxidase/dehydrogenase (ZMCKX1) reactions. This new research partnership combines complementary research expertise of the two laboratories. The research will examine the role of electron flux within specific compartments of plant cells in an effort to understand features of metabolic control of cytokinin degradation and regeneration of active cytokinin oxidase/dehydrogenase. The main hypothesis of this proposal is that plants contain specific bioactive cofactors that are capable of regenerating active cytokinin oxidase/dehydrogenase enzymes by accepting electrons during catalysis of cytokinins. We will determine the subcellular location of the enzyme, precisely characterize the redox potential of the enzyme for comparison to the properties of putative bioactive cofactors, and perform depletion experiments to initially identify the reaction-enhancing bioactive cofactor used in plants. This research directly addresses the question of specificity for the ZmCKX1 bioactive cofactor and defines the range of electrochemical redox potentials for bioactive cofactor candidates. Subcellular localization of ZmCKX1 and redox characterization will independently contribute to our understanding of the biochemical and physiological properties of the enzyme and processes that occur during plant development. The partnership also provides unique and valuable opportunities for reciprocal exchange of undergraduate and graduate students who will gain educational and technical training, and research experience at the international level.