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Medientyp:
E-Artikel
Titel:
C1 Metabolism and Chlorophyll Synthesis: The Mg-Protoporphyrin IX Methyltransferase Activity Is Dependent on the Folate Status
Beteiligte:
Van Wilder, Valérie;
De Brouwer, Veerle;
Loizeau, Karen;
Gambonnet, Bernadette;
Albrieux, Catherine;
Van Der Straeten, Dominique;
Lambert, Willy E.;
Douce, Roland;
Block, Maryse A.;
Rebeille, Fabrice;
Ravanel, Stéphane
Erschienen:
Blackwell Publishing, 2009
Erschienen in:
The New Phytologist, 182 (2009) 1, Seite 137-145
Sprache:
Englisch
ISSN:
0028-646X;
1469-8137
Entstehung:
Anmerkungen:
Beschreibung:
• 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.