BPS2026 – Cryo-EM of membrane protein complexes from and within mitochondria

Biological energy conversion in mitochondria depends on the large membrane protein complexes of the inner mitochondrial membrane. For several years, cryo-EM has been the main tool for investigating the structure of these complexes at high resolution, as a prerequisite for understanding how they work. Single-particle cryo-EM of the Polytomella ATP synthase dimer purified from the unicellular flagellate Polytomella sp has resolution maps of the membrane-spanning rotor/stator complex at ∼2 Å resolution. 3D classification reveals different rotary states with well-resolved water molecules, tracing the paths of the protons that drive rotary catalysis. In addition, we use cryoET of FIB lamellae to determine the in situ structure of ATP synthase dimers and complex I in Polytomella mitochondria. The current sub-tomogram average maps of ATP synthase and complex I stand at 4.2 Å and ∼5.7 Å resolution, respectively.