Light-activation of NADP-malate dehydrogenase: A highly controlled process for an optimized function
| Autor: | Aymeric Goyer, Kenth Johansson, Paulette Decottignies, Jean-Pierre Jacquot, P. Le Maréchal, E. Ruelland, I. Schepens, Emmanuelle Issakidis-Bourguet, Myroslawa Miginiac-Maslow, M. Lemaire-Chamley |
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| Přispěvatelé: | Institut de biotechnologie des plantes (IBP), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2008 |
| Předmět: |
0106 biological sciences
Physiology [SDV]Life Sciences [q-bio] Dehydrogenase Plant Science Nicotinamide adenine dinucleotide 01 natural sciences Malate dehydrogenase Cofactor 03 medical and health sciences chemistry.chemical_compound Genetics ComputingMilieux_MISCELLANEOUS Ferredoxin 030304 developmental biology chemistry.chemical_classification 0303 health sciences biology Active site Cell Biology General Medicine Enzyme chemistry Biochemistry Regulatory sequence biology.protein 010606 plant biology & botany |
| Zdroj: | Physiologia Plantarum Physiologia Plantarum, Wiley, 2000, 110 (3), pp.322-329. ⟨10.1111/j.1399-3054.2000.1100306.x⟩ |
| ISSN: | 0031-9317 1399-3054 |
| Popis: | The chloroplastic nicotinamide adenine dinucleotide phosphate-malate dehydrogenase (NADP-MDH) (EC 1.1.1.82), a key enzyme of photosynthetic carbon assimilation of the C4 NADP-malic enzyme type plants, is strictly regulated by light through the ferredoxin-thioredoxin system. It is inactive in the dark, in the oxidized form, and activated in the light by the reduction of specific regulatory disulfides. A site-directed mutagenesis approach allowed localization of the regulatory disulfides in the N- and C-terminal sequence extensions conserved in all the light-regulated chloroplastic malate dehydrogenases. These extensions do not exist in the permanently active NAD-dependent MDHs (EC 1.1.1.37). Biochemical characterization of the mutants and elimination of negative charges at the C-terminus provided evidence for auto-inhibition of the oxidized enzyme by its C-terminal end through interaction with the active site and showed that the more compact structure of the oxidized dimer was linked to the presence of the N-terminal disulfide. The recently published 3-dimensional structures of the oxidized enzyme confirmed the location of the regulatory disulfides and fully support the auto-inhibition hypothesis. Indeed, the C-terminus is trapped inside the active site, interacting with active-site residues, and the N-termini are inserted at the dimer contact area where they are bound by hydrophobic interactions with both subunits. The physiological function of such complex regulation is discussed. |
| Databáze: | OpenAIRE |
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