Abstract
The mitochondrial ATP synthase fuels eukaryotic cells with chemical energy. Here we report the cryo-EM structure of a divergent ATP synthase dimer from mitochondria of Euglena gracilis, a member of the phylum Euglenozoa that also includes human parasites. It features 29 different subunits, 8 of which are newly identified. The membrane region was determined to 2.8 Å resolution, enabling the identification of 37 associated lipids, including 25 cardiolipins, which provides insight into protein-lipid interactions and their functional roles. The rotor-stator interface comprises four membrane-embedded horizontal helices, including a distinct subunit a. The dimer interface is formed entirely by phylum-specific components, and a peripherally associated subcomplex contributes to the membrane curvature. The central and peripheral stalks directly interact with each other. Last, the ATPase inhibitory factor 1 (IF1) binds in a mode that is different from human, but conserved in Trypanosomatids.
Highlights
The mitochondrial ATP synthase is a membrane protein complex that generates most of the ATP in eukaryotic cells
Loss of ATP synthase dimers results in aberrant cristae morphology, indicating that dimers are required for membrane bending and proper cristae formation in mitochondria (Davies et al, 2012; Paumard et al, 2002)
The analysis revealed that the ATP synthase in E. gracilis has 29 different protein subunits, 13 of which are only found in organisms of the same family
Summary
The mitochondrial ATP synthase is a membrane protein complex that generates most of the ATP in eukaryotic cells. The torque of the rotor against the stator subunits induces conformational changes in the (ab) headpiece, thereby triggering catalysis (Abrahams et al, 1994; Noji et al, 1997). The mitochondrial ATP synthase forms dimers, which in turn associate into dimer rows along the high-curvature membrane regions of the cristae (Davies et al, 2012; Paumard et al, 2002; Strauss et al, 2008). Loss of ATP synthase dimers results in aberrant cristae morphology, indicating that dimers are required for membrane bending and proper cristae formation in mitochondria (Davies et al, 2012; Paumard et al, 2002)
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