Dramatic changes in mitochondrial subcellular location and morphology accompany activation of the CO 2 concentrating mechanism

作者：Justin Findinier, Lydia‐Marie Joubert, Neda Fakhimi, Michael F. Schmid, Andrey V. Malkovskiy, Wah Chiu, Adrien Burlacot, Arthur Grossman · 发表于：Proceedings of the National Academy of Sciences · 年份：2024 · DOI：10.1073/pnas.2407548121 · 被引用次数：19 · 研究领域：Photosynthetic Processes and Mechanisms、Algal biology and biofuel production、Marine and coastal ecosystems

Dynamic changes in intracellular ultrastructure can be critical for the ability of organisms to acclimate to environmental conditions. Microalgae, which are responsible for ~50% of global photosynthesis, compartmentalize their Ribulose 1,5 Bisphosphate Carboxylase/Oxygenase (Rubisco) into a specialized structure known as the pyrenoid when the cells experience limiting CO 2 conditions; this compartmentalization is a component of the CO 2 Concentrating Mechanism (CCM), which facilitates photosynthetic CO 2 fixation as environmental levels of inorganic carbon (Ci) decline. Changes in the spatial distribution of mitochondria in green algae have also been observed under CO 2 limitation, although a role for this reorganization in CCM function remains unclear. We used the green microalga Chlamydomonas reinhardtii to monitor changes in mitochondrial position and ultrastructure as cells transition between high CO 2 and Low/Very Low CO 2 (LC/VLC). Upon transferring cells to VLC, the mitochondria move from a central to a peripheral cell location and orient in parallel tubular arrays that extend along the cell’s apico-basal axis. We show that these ultrastructural changes correlate with CCM induction and are regulated by the CCM master regulator CIA5. The apico-basal orientation of the mitochondrial membranes, but not the movement of the mitochondrion to the cell periphery, is dependent on microtubules and the MIRO1 protein, with the latter involved in membrane–microtubule interactions. ...