title: C1 metabolism and chlorophyll synthesis: the Mg-protoporphyrin IX methyltransferase activity is dependent on the folate status.
abstract: * Tetrahydrofolate derivatives are central cofactors of C1 metabolism. Using methotrexate as a specific inhibitor of folate biosynthesis, we altered the folate status in 10-d-old etiolated pea (Pisum sativum) leaves and followed the rate of chlorophyll synthesis upon illumination. * In our conditions, the folate concentration decreased only from 5.7 to 4.2 nmol g(-1) FW, but the amount of chlorophyll after 24 h of illumination was reduced 2.5 times. Folate status and rate of chlorophyll synthesis were apparently correlated through the methyl cycle. * Indeed, we observed that methyl-tetrahydrofolate was the folate derivative most affected by the treatment; the decrease of methyl-tetrahydrofolate was associated with a sharp rise in homocysteine and S-adenosylhomocysteine concentrations, which are normally maintained at very low values, shifting the methylation index (S-adenosylmethionine/S-adenosylhomocysteine ratio) from 7 to 1; the decrease of the methylation index reduced by a factor of 3 the activity of the Mg-protoporphyrin IX methyltransferase (CHLM), an essential enzyme for chlorophyll synthesis. CHLM gene expression and protein concentration remained unchanged, suggesting that this inhibition relied essentially on metabolic regulation. * These results point out that an even moderate change in the folate status may affect plant development and adaptation.
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Van Wilder
authors.affiliation: Laboratory of Toxicology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: De Brouwer
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Karen
authors.initials: K
authors.lastname: Loizeau
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Gambonnet
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Albrieux
authors.affiliation: Unit Plant Hormone Signaling and Bioimaging, Department of Molecular Genetics, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
authors.forename: Dominique
authors.initials: D
authors.lastname: Van Der Straeten
authors.affiliation: Laboratory of Toxicology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
authors.forename: Willy E
authors.initials: WE
authors.lastname: Lambert
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Douce
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Maryse A
authors.initials: MA
authors.lastname: Block
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Rebeille
authors.affiliation: Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ravanel
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects; D002244:Carbon / Q000378:metabolism*; D002734:Chlorophyll / Q000096:biosynthesis*; D005492:Folic Acid / Q000378:metabolism*; D008027:Light; D008727:Methotrexate / Q000494:pharmacology; D008745:Methylation / Q000187:drug effects / Q000528:radiation effects; D008780:Methyltransferases / Q000378:metabolism*; D018532:Pisum sativum / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects; D013763:Tetrahydrofolates / Q000737:chemistry / Q000378:metabolism
chemical_list: D013763:Tetrahydrofolates; D002734:Chlorophyll; D002244:Carbon; D005492:Folic Acid; D008780:Methyltransferases; C060234:magnesium-protoporphyrin methyltransferase; D008727:Methotrexate