Photosynthesis gone astray

30 May 2023

Molecular biologists reveal the physiological significance of an inhibitor degradation system in photosynthesis.

The enzyme Rubisco in photosynthesis is responsible for nearly all carbon dioxide fixation in the global carbon cycle. However, the enzymatic reaction is susceptible to the formation of inhibitors that bind to Rubisco's active sites, impairing carbon dioxide fixation. Thus, carbon-fixing organisms possess a repair system in which the inhibitors are first released from the active sites and subsequently degraded.

A team of molecular biologists led by PD Dr. Thilo Rühle and Professor Dario Leister has now demonstrated the physiological importance of the inhibitor degradation process in plants. Using the plant model organism Arabidopsis thaliana, it was shown that two different enzymes are responsible for the degradation of an inhibitor called xylulose-1,5-bisphosphate, and the loss of both enzymes led to reduced growth and impaired photosynthesis.

The results highlight that efficient photosynthesis is only possible through functional cooperation of the enzymes involved in the release and degradation of Rubisco inhibitors. In the future, the insights gained from this study can be utilized to optimize carbon dioxide fixation in biological systems.

Dario Leister, Anurag Sharma, Natalia Kerber, Thomas Nägele, Bennet Reiter, Viviana Pasch, Simon Beeh, Peter Jahns, Roberto Barbato, Mathias Pribil, Thilo Rühle: An ancient metabolite damage-repair system sustains photosynthesis in plants. Nature Communications, 2023

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