Cryo-electron tomography of C. elegans mitochondria reveals how the ATP synthase dimer interface shapes crista membranes

Mitochondrial ATP synthases form rows of dimers, which induce membrane curvature to give cristae their characteristic lamellar or tubular morphology. The angle formed between the central stalks of ATP synthase dimers varies between species. Using cryo-electron tomography and sub-tomogram averaging, we determined the structure of the ATP synthase dimer from the nematode worm C. elegans. We showed that the angle formed by the ATP synthase dimer is different to previously determined structures. The consequences of species-specific differences at the dimer interface were investigated by comparing mitochondrial morphology between C. elegans and S. cerevisiae. We reveal that a larger ATP synthase dimer angle in C. elegans is consequent with more lamellar (flatter) cristae compared to yeast. The underlying cause of this difference was investigated by generating an atomic model of the C. elegans ATP synthase dimer by homology modelling and comparing it to an existing S. cerevisiae structure. We reveal extensions and rearrangements of C. elegans subunits that maintain the dimer interface. We propose that increased dimer angles resulting in flatter cristae could provide an energetic advantage for species that inhabit variable-oxygen environments. ### Competing Interest Statement The authors have declared no competing interest.