As if ATP synthase was not amazing enough, a team of scientists in Germany now tells us they are arranged in rows with other equipment to optimize performance. From electron micrographs of intact mitochondria, they were able to detect the rotary engines of ATP synthase and other parts of the respiratory chain. Their diagram in an open-source paper in PNAS looks for all the world like a factory.
CEH has reported on ATP synthase many times (for concise explanation with animation, see CMI). Your body, and every other living thing on earth, depends on a steady supply of the ATP “energy pellets” they synthesize. The two-part rotary engines rely on a constant flow of protons (proton motive force, or pmf). These protons are produced by other engines, Complex I (NADH dehydrogenase; for structure of this piston engine, see 07/06/2010), Complex III (cytochrome c reductase), and Complex IV (cytochromec oxidase), through a series of mechanical and chemical reactions. The protons enter ATP synthase through its bottom structure, called F0, which is embedded in the mitochondrial membrane, causing it to rotate (the authors said it “works like a proton-driven turbine”). A stator and central stalk transfer the energy to the top part, F1, where three catalytic centers, arranged like orange slices, take in ADP and phosphate to create ATP – molecules with stored energy that travel throughout the cell to power almost everything.
Each of these molecular machines are wonders of design efficiency in themselves. The new paper by Davies et al. augments that wonder by showing how they are all arranged for maximum performance.1 In order to save words, we are attaching their diagram (Figure 5) from the open-source paper; readers are encouraged to go to the source provided for caption and details.1 The proton-pumping machines (green) are arranged along folds of the cristae (blue) so that the protons don’t wander away from the ATP synthase machines (yellow). Since Complexes I, III, and IV act as proton “sources” and ATP synthase as proton “sinks”, a flow is set up toward the tight folds where the ATP synthase (yellow) are located….
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