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Kopečný D, Končitíková R, Popelka H, Briozzo P, Vigouroux A, Kopečná M, Zalabák D, Šebela M, Skopalová J, Frébort I, Moréra S. Kinetic and structural investigation of the cytokinin oxidase/dehydrogenase active site. FEBS J 2015; 283:361-77. [PMID: 26519657 DOI: 10.1111/febs.13581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/26/2015] [Accepted: 10/28/2015] [Indexed: 12/24/2022]
Abstract
Cytokinins are hormones that regulate plant development and their environmental responses. Their levels are mainly controlled by the cytokinin oxidase/dehydrogenase (CKO), which oxidatively cleaves cytokinins using redox-active electron acceptors. CKO belongs to the group of flavoproteins with an 8α-N1-histidyl FAD covalent linkage. Here, we investigated the role of seven active site residues, H105, D169, E288, V378, E381, P427 and L492, in substrate binding and catalysis of the CKO1 from maize (Zea mays, ZmCKO1) combining site-directed mutagenesis with kinetics and X-ray crystallography. We identify E381 as a key residue for enzyme specificity that restricts substrate binding as well as quinone electron acceptor binding. We show that D169 is important for catalysis and that H105 covalently linked to FAD maintains the enzyme's structural integrity, stability and high rates with electron acceptors. The L492A mutation significantly modulates the cleavage of aromatic cytokinins and zeatin isomers. The high resolution X-ray structures of ZmCKO1 and the E381S variant in complex with N6-(2-isopentenyl)adenosine reveal the binding mode of cytokinin ribosides. Those of ZmCKO2 and ZmCKO4a contain a mobile domain, which might contribute to binding of the N9 substituted cytokinins.
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Affiliation(s)
- David Kopečný
- Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Radka Končitíková
- Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Hana Popelka
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Pierre Briozzo
- Institut Jean-Pierre Bourgin, UMR1318 INRA, AgroParisTech, Versailles, France
| | - Armelle Vigouroux
- Institute for Integrative Biology of the Cell (I2BC), CNRS-CEA-Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Martina Kopečná
- Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - David Zalabák
- Department of Molecular Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Marek Šebela
- Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Jana Skopalová
- Department of Analytical Chemistry, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Ivo Frébort
- Department of Molecular Biology, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Solange Moréra
- Institute for Integrative Biology of the Cell (I2BC), CNRS-CEA-Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
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Kano K, Konse T, Kubota T. The Curve Fitting Analysis of D.c. and A.c. Voltammograms of a Two-step Surface-redox Reaction. The Application to the Surface-redox System of Adriamycin Adsorbed on a Pyrolytic Graphite Electrode. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1985. [DOI: 10.1246/bcsj.58.1879] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kano K, Konse T, Nishimura N, Kubota T. Electrochemical Properties of Adriamycin Adsorbed on a Mercury Electrode Surface. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1984. [DOI: 10.1246/bcsj.57.2383] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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