These four biological molecules are essential to all life on Earth.
They originated more than 3 Billion years ago during the Proterozoic Era, in a common ancestor of Bacteria, Archaea, and Eukaryota. Together these molecules form the fundamental pattern of the fractal of life; they are specialized machines that replicate each other and produce an endless variety of new forms. They have evolved over trillions of generations into extraordinarily complex arrangements that consume energy, organize, and reproduce.
‘Smallest rotary motor in biology, the ATP synthase.
All the work done in your body is fueled by breaking a chemical bond in ATP, the “currency of energy”. Did you know that you convert your body weight (or an estimated 50 kg) of ATP per day?!
Where does this ATP come from?
It is synthesized by an incredibly sophisticated molecular machine, the ATP synthase, embedded in the inner membrane of our mitochondria. Energy from the oxidation of food results in protons being pumped across the membrane to create a proton gradient. The protons drive the rotation of a circular ring of proteins in the membrane that in turn move a central shaft. The shaft interacts sequentially with one of 3 catalytic sites within a hexamer, making ATP (little butterflies in the movie!). The ATP synthase rotates about 150 times/second
Notice the rotation is slower with longer rods. The rotor produces a torque of 40 pN nm (40 pico Newtons x nanometer), irrespective of the load. This would be the force you would need to rotate a 500 m long rod while standing at the bottom of a large swimming pool at the rate shown in the movie.
How did this amazing rotor evolve?
The hexameric structure is related to DNA helicases that rotate along the DNA double helix, using ATP to unzip the two strands apart. The H+ motor has precedence in flagella motors that use proton gradients to drive rotation of long filaments, allowing bacteria to tumble through their surroundings. At some point, a H+ driven motor came together with a helicase like hexamer to create a rotor driving the hexamer in reverse, to synthesize ATP.
The 1997 Nobel prize in Chemistry was awarded to John Walker and Paul Boyer for solving the structure and cyclical mechanism of the ATP synthase, respectively. This amazing enzyme was also the subject of my own Ph.D. thesis, and my first love!’