Séminaire IBIP

Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)

Jeudi 13 février 2025 à 14h00 –Amphi 208

Martin Groth

Institute of Functional Epigenetics, Helmholtz Munich, Neuherberg, 85764, Germany.
Correspondence: martin.groth@helmholtz-munich.de

Folate metabolism links DNA methylation to photorespiration

Photorespiration, the metabolic process initiated by the oxygenation reaction of RuBisCO, leads to CO2 release and energy consumption that reduce net photosynthesis rates by up to 50 %. Therefore, photorespiration has long been regarded as simply wasteful but recent studies are starting to draw a more differentiated picture. Focusing on the interactions of metabolism and epigenetic regulation in Arabidopsis thaliana, we observed that suppressing photorespiration by increasing the ambient CO2 concentration leads to genome-wide changes in DNA methylation. We have previously shown that MTHFD1, a central enzyme in folate-mediated C1 metabolism (FOCM), is required for DNA methylation. Subsequent analyses revealed that the mthfd1 phenotype is sensitive to day length and suppressed by introducing a second mutation in a gene we named SUPPRESSOR OF MTHFD1 (SUMD). Interestingly, SUMD encodes an enzyme in the formate-dependent branch of FOCM, which we confirmed by enzymatic assays. As photorespiration is a source of formate, we hypothesized that the interaction of photorespiration and DNA methylation is mediated by SUMD and MTHFD1. Using isotope tracing with 13C-labeled formate we confirmed that formate is fixed in the cytosolic folate cycle in a SUMD- and MTHFD1-dependent way and contributes C1 for DNA methylation. By integrating metabolomics and epigenomics data, we propose a new mechanism that regulates C1 fluxes and DNA methylation dynamics in a light- and CO2-dependent way.