Abstract
SummaryWe determined the structure of a complete, dimeric F1Fo-ATP synthase from yeast Yarrowia lipolytica mitochondria by a combination of cryo-EM and X-ray crystallography. The final structure resolves 58 of the 60 dimer subunits. Horizontal helices of subunit a in Fo wrap around the c-ring rotor, and a total of six vertical helices assigned to subunits a, b, f, i, and 8 span the membrane. Subunit 8 (A6L in human) is an evolutionary derivative of the bacterial b subunit. On the lumenal membrane surface, subunit f establishes direct contact between the two monomers. Comparison with a cryo-EM map of the F1Fo monomer identifies subunits e and g at the lateral dimer interface. They do not form dimer contacts but enable dimer formation by inducing a strong membrane curvature of ∼100°. Our structure explains the structural basis of cristae formation in mitochondria, a landmark signature of eukaryotic cell morphology.
Highlights
The mitochondrial F1Fo-ATP synthase produces most of the ATP in the cell by rotary catalysis and plays a crucial role in severe human neurodegenerative disorders (Kucharczyk et al, 2009)
We determined the structure of a complete, dimeric F1Fo-ATP synthase from yeast Yarrowia lipolytica mitochondria by a combination of cryoelectron microscopy (cryo-EM) and X-ray crystallography
Our structure explains the structural basis of cristae formation in mitochondria, a landmark signature of eukaryotic cell morphology
Summary
The mitochondrial F1Fo-ATP synthase produces most of the ATP in the cell by rotary catalysis and plays a crucial role in severe human neurodegenerative disorders (Kucharczyk et al, 2009). Dimers of the ATP synthase shape the inner mitochondrial membrane and mediate cristae formation (Davies et al., 2012; Paumard et al, 2002). Together with the c-ring rotor, the horizontal helices of subunit a create two aqueous half-channels on either side of the membrane (Allegretti et al, 2015; Kuhlbrandt and Davies, 2016). The c subunits in the rotor ring bind and release protons as the ring rotates through the alternating hydrophobic environment of the lipid bilayer and the aqueous environment of the halfchannels (Allegretti et al, 2015; Meier et al, 2011, 2005; Pogoryelov et al, 2010; Symersky et al, 2012), thereby generating the torque for ATP synthesis
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