Max Planck Institute of Biophysics
Mitochondria are the powerhouses of eukaryotic cells and the main site of ATP synthesis in cells performing aerobic respiration. Located in the cristae membranes, the ancient nano-machine, ATP synthase, uses the energy stored in an electrochemical gradient of protons to catalyses the conversion of ADP and inorganic phosphate to ATP. The mechanism of proton-coupled ATP synthesis has remained poorly understood for decades due to the lack of structural information on the membrane-embedded subunits of this complex. By single-particle cryo-EM analysis, we have revealed a bundle of long horizontal, membrane intrinsic helices adjacent to the rotor ring of a mitochondrial ATP synthase thereby providing a structural basis for understanding how proton movement across a membrane drives ATP synthesis. Moreover, by electron cryo-tomography and subtomogram averaging we have shown that mitochondrial ATP synthases play a major role in shaping cristae, which in turn affects cellular fitness.