Chloroplast ATP synthase structure generated through cryo-EM ($) (Science)

Green plants use photosynthesis to covert light into ATP (adenosine triphosphate) through the molecular action of the chloroplast F₁F_o ATP synthase (cF₁F_o). The ATP synthesis happens in the hydrophilic head (c F₁) and is powered by the cF_o rotary motor located in the photosynthetic membrane. This rotary motor is driven by the electrochemical gradient maintained across the membrane. Crystallization of this large and dynamic membrane-bound protein has been difficult so no high-resolution structure of an entire, functional ATP synthase has been generated. Thus, Hahn and colleagues used a lipid nanodisc-based purification method to generate a high-resolution spinach c F₁F_o structure (2.9 Å for cF₁, 3.4 Å for cF_o) through cryo-electron microscopy (cryo-EM). They also characterize three functional states that are involved in rotary ATP synthesis. The features of cF₁F_o are similar to ATP synthases in mitochondria and bacteria, even though the evolutionary distance is about a billion years or more.  (Summary by Julia Miller) Science  10.1126/science.aat4318