Exploring mitochondrial molecular architecture across eukaryotes

Presented by Florent WALTZ

In mitochondria, five membrane-bound complexes, collectively known as the respiratory chain, regenerate ATP from ADP by coordinating electron transfer with proton pumping. The native organization of these complexes into higher-order structures remains a subject of ongoing debate.

Using focused ion beam (FIB) milling combined with cryo-electron tomography (cryo-ET), we investigate the native architecture and organization of mitochondrial complexes in situ. This approach provides unprecedented, high-resolution snapshots of the mitochondrial landscape in its near-native state.We previously revealed the detailed spatial arrangement of respiratory complexes in the green alga Chlamydomonas reinhardtii, where ATP synthases and respiratory complexes segregate into curved and flat crista membrane domains, respectively. In this organism, respiratory complexes I, III, and IV assemble into a single type of supercomplex.

Now, we explore how these complexes are organized across diverse organisms and, using a mutant-based approach, investigate the potential roles of these supercomplexes in maintaining efficient mitochondrial function.