How respiratory complexes and ATP synthase co-assemble to build cristae

Mitochondrial oxidative phosphorylation (OXPHOS) is often organized into spatially segregated domains, with ATP synthase (complex V, CV) oligomers shaping highly curved cristae rims and respiratory chain complexes I-IV (CI-CIV) occupying flatter membrane regions(1,2). Building on our recent identification of a bona fide ETC-ATP synthase supercomplex (see accompanying manuscript), here we determine how such assemblies are deployed into long-range, periodic OXPHOS arrays on native membranes. By integrating cryo-electron microscopy (cryo-EM) and cryo-electron tomography (cryo-ET), we resolve multiple CIICIV2CV-based supercomplexes that act as endcaps for ATP synthase dimer (CV2) rows from the mitochondria of the kinetoplastid parasite Leishmania tarentolae. We show that repeating units of endcapped-rows stack with defined registers to tile the discoidal cristae rim, establishing a membrane-scale architectural program that couples respiratory-chain organization to cristae morphology. Subtomogram averaging validates these assemblies in situ and reveals their characteristic orientation and spacing on the crista rim. Together, these data extend the CIICIV2CV framework from molecular mechanism to mesoscale architecture and suggest that kinetoplastids achieve stable discoidal cristae by constraining ATP synthase row growth through CIICIV2CV-mediated endcapping and ordered packing.