High Resolution Investigation of Mitochondrial Molecular Architecture using Cryo-Electron Tomography

Focused Ion Beam (FIB) milling combined with cryo-electron tomography (cryo-ET) are structural biology techniques that can unravel the native organization and structures of molecular complexes directly inside cells. In the lab, we use these techniques to investigate organelle biology, focused on photosynthetic organisms. Combining cryo-ET with biochemistry and cryo-electron microscopy (cryo-EM), we aim to understand the main mitochondrial complexes across photosynthetic lineages, examining them from the cellular to atomic level. In previous work, we applied these complementary approaches to investigate how mitochondrial translation is organized in the green alga Chlamydomonas reinhardtii, the model unicellular organism used in the lab. Our findings revealed it as an extreme example of ribosome evolution and species-specific adaptation, with cryo-ET providing insights into its native association and structure at the inner mitochondrial membrane. Now, in a collaborative project, we expanded our investigation by capturing a large high-resolution dataset covering the entire Chlamydomonas cell. Focusing on mitochondria, we analyzed the organization of their major molecular complexes, notably the respiratory chain, revealing structures and architectures never observed before.