The Photorespiratory Metabolite 2-Phosphoglycolate Regulates Photosynthesis and Starch Accumulation in Arabidopsis

The Calvin-Benson cycle and its photorespiratory repair shunt are in charge of nearly all biological CO2 fixation on Earth. They interact functionally and via shared carbon flow on several levels including common metabolites, transcriptional regulation, and response to environmental changes. 2-Phosp...

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Bibliographic Details
Published in:The Plant cell 2017-10, Vol.29 (10), p.2537-2551
Main Authors: Flügel, Franziska, Timm, Stefan, Arrivault, Stéphanie, Florian, Alexandra, Stitt, Mark, Fernie, Alisdair R., Bauwe, Hermann
Format: Article
Language:English
Subjects:
Accumulation
Carbohydrate metabolism
Carbohydrates
Carbon
Carbon dioxide
Carbon dioxide fixation
Carbon sequestration
Conductance
Environmental changes
Environmental regulations
Gas exchange
Gene regulation
Impact analysis
Metabolism
Metabolites
Phosphatase
Phosphates
Photosynthates
Photosynthesis
Regeneration
Resistance
Starch
Stomata
Stomatal conductance
Transcription
Triose-phosphate isomerase
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Summary:The Calvin-Benson cycle and its photorespiratory repair shunt are in charge of nearly all biological CO2 fixation on Earth. They interact functionally and via shared carbon flow on several levels including common metabolites, transcriptional regulation, and response to environmental changes. 2-Phosphoglycolate (2PG) is one of the shared metabolites and produced in large amounts by oxidative damage of the CO2 acceptor molecule ribulose 1,5-bisphosphate. It was anticipated early on, although never proven, that 2PG could also be a regulatory metabolite that modulates central carbon metabolism by inhibition of triose-phosphate isomerase. Here, we examined this hypothesis using transgenic Arabidopsis thaliana lines with varying activities of the 2PG-degrading enzyme, 2PG phosphatase, and analyzing the impact of this intervention on operation of the Calvin-Benson cycle and other central pathways, leaf carbohydrate metabolism, photosynthetic gas exchange, and growth. Our results demonstrate that 2PG feeds back on the Calvin-Benson cycle. It also alters the allocation of photosynthates between ribulose 1,5-bisphosphate regeneration and starch synthesis. 2PG mechanistically achieves this by inhibiting the Calvin-Benson cycle enzymes triose-phosphate isomerase and sedoheptulose 1,7-bisphosphate phosphatase. We suggest this may represent one of the control loops that sense the ratio of photorespiratory to photosynthetic carbon flux and in turn adjusts stomatal conductance, photosynthetic CO2 and photorespiratory O2 fixation, and starch synthesis in response to changes in the environment.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.17.00256