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Photorespiration is the second largest carbon flux in most leaves and is integrated into metabolism broadly including one-carbon (C1) metabolism. Photorespiratory intermediates such as serine and others may serve as sources of C1 units, but it is unclear to what degree this happens in vivo, whether altered photorespiration changes flux to C1 metabolism, and if so through which intermediates. To clarify these questions, we quantified carbon flux from photorespiration to C1 metabolism using 13CO2 labelling and isotopically non-stationary metabolic flux analysis in Arabidopsis thaliana under different O2 concentrations which modulate photorespiration. The results revealed that ~5.8% of assimilated carbon passes to C1 metabolism under ambient photorespiratory conditions, but this flux greatly decreases under limited photorespiration. Furthermore, the primary carbon flux from photorespiration to C1 metabolism is through serine. Our results provide fundamental insight into how photorespiration is integrated into C1 metabolism, with possible implications for C1 metabolic response to climate change.
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This content will become publicly available on September 9, 2026
Mitochondrial formate dehydrogenase constitutes a one carbon shunt linking mitochondrial and cytosolic one carbon metabolism
The transfer of one-carbon (C1) units is an integral part of cellular metabolism and is essential for the biosynthesis of nucleotides-, amino acids, and cofactors, as well as for cellular methylation reactions. Within the plant cell, mitochondria are considered to be the hub of one-carbon metabolism, but the mechanisms and fluxes that distribute C1 units from the mitochondria throughout the cell are unknown. Formate, the anion of formic acid, is an intermediate of C1 metabolism and is converted to C1-tetrahydrofolate intermediates (C1 folates) or oxidized to CO2 by formate dehydrogenase. The existence of formate dehydrogenase in plant cells challenges the formate exchange between mitochondria and the cytosol, a basic principle of eukaryotic cellular and organellar C1 metabolism. Based on the biochemical and physiological characterization of Arabidopsis thaliana formate dehydrogenase 1 (FDH1), we propose an FDH1-regulated C1 shunt linking mitochondrial and cytosolic C1 metabolism by formate exchange. Finally, we give a perspective on a cellular serine/formate shuttle that allows the distribution and transfer of C1 units according to the redox state within the compartments.
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- Award ID(s):
- 2015828
- PAR ID:
- 10639810
- Publisher / Repository:
- Oxford press
- Date Published:
- Journal Name:
- Plant physiology
- ISSN:
- 0032-0889
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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