The green algae CO2 concentrating mechanism and photorespiration jointly operate during acclimation to low CO2

作者：Ousmane Dao, Marie Bertrand, Saleh Alseekh, Florian Veillet, Pascaline Auroy, Phuong-Chi Nguyen, Bertrand Légeret, Virginie Epting, Amélie Morin, Stéphan Cuiné, Caroline Monteil, Luke C. M. Mackinder, Adrien Burlacot, Anja Krieger‐Liszkay, Andreas P.M. Weber, Alisdair R. Fernie, Gilles Peltier, Yonghua Li‐Beisson · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-60525-7 · 被引用次数：23 · 研究领域：Algal biology and biofuel production、Marine and coastal ecosystems、Photosynthetic Processes and Mechanisms

Abstract Due to low availability of CO 2 in aquatic environment, microalgae have evolved a CO 2 concentrating mechanism (CCM). It has long been thought that operation of CCM would suppress photorespiration by increasing the CO 2 concentration at the Rubisco active site, but experimental evidence is scarce. To better explore the function of photorespiration in algae, we first characterized a Chlamydomonas reinhardtii mutant defected in low-CO 2 inducible 20 (LCI20) and show that LCI20 is a chloroplast-envelope glutamate/malate transporter playing a role in photorespiration. By monitoring growth and glycolate excretion in mutants deficient in either CCM or photorespiration, we conclude that: ( i. ) CCM induction does not depend on photorespiration, ( ii. ) glycolate excretion together with glycolate dehydrogenase down-regulation prevents the toxic accumulation of non-metabolized photorespiratory metabolites, and ( iii .) photorespiration is active at low CO 2 when the CCM is operational. This work provides a foundation for a better understanding of the carbon cycle in the ocean where significant glycolate concentrations have been found.