1W1Q

Plant Cytokinin Dehydrogenase in Complex with Isopentenyladenine

Summary for 1W1Q

• Entry DOI: 10.2210/pdb1w1q/pdb
• Related: 1W1O 1W1R 1W1S
• Descriptor: CYTOKININ DEHYDROGENASE 1, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, FLAVIN-ADENINE DINUCLEOTIDE, ... (6 entities in total)
• Functional Keywords: flavin, cytokinin, oxidoreductase, flavoprotein, fad
• Biological source: ZEA MAYS (MAIZE)
• Total number of polymer chains: 1
• Total formula weight: 59345.31

Authors

Malito, E.,Mattevi, A. (deposition date: 2004-06-23, release date: 2004-08-26, Last modification date: 2024-11-13)

Primary citation

Malito, E.,Coda, A.,Bilyeu, K.,Fraaije, M.W.,Mattevi, A.
Structures of Michaelis and Product Complexes of Plant Cytokinin Dehydrogenase: Implications for Flavoenzyme Catalysis
J.Mol.Biol., 341:1237-, 2004

PubMed Abstract: Cytokinins form a diverse class of compounds that are essential for plant growth. Cytokinin dehydrogenase has a major role in the control of the levels of these plant hormones by catalysing their irreversible oxidation. The crystal structure of Zea mays cytokinin dehydrogenase displays the same two-domain topology of the flavoenzymes of the vanillyl-alcohol oxidase family but its active site cannot be related to that of any other family member. The X-ray analysis reveals a bipartite architecture of the catalytic centre, which consists of a funnel-shaped region on the protein surface and an internal cavity lined by the flavin ring. A pore with diameter of about 4A connects the two active-site regions. Snapshots of two critical steps along the reaction cycle were obtained through the structural analysis of the complexes with a slowly reacting substrate and the reaction product, which correspond to the states immediately before (Michaelis complex) and after (product complex) oxidation has taken place. The substrate displays a "plug-into-socket" binding mode that seals the catalytic site and precisely positions the carbon atom undergoing oxidation in close contact with the reactive locus of the flavin. A polarising H-bond between the substrate amine group and an Asp-Glu pair may facilitate oxidation. Substrate to product conversion results in small atomic movements, which lead to a planar conformation of the reaction product allowing double-bond conjugation. These features in the mechanism of amine recognition and oxidation differ from those observed in other flavin-dependent amine oxidases.

PubMed: 15321719
DOI: 10.1016/J.JMB.2004.06.083

Experimental method

X-RAY DIFFRACTION (1.8 Å)