Bacterial F-type ATP synthases follow a well-choreographed assembly pathway

F-type ATP synthases are multiprotein complexes composed of two separate coupled motors (F-1 and F-O) generating adenosine triphosphate (ATP) as the universal major energy source in a variety of relevant biological processes in mitochondria, bacteria and chloroplasts. While the structure of many ATPases is solved today, the precise assembly pathway of F1FO-ATP synthases is still largely unclear. Here, we probe the assembly of the F-1 complex from Acetobacterium woodii. Using laser induced liquid bead ion desorption (LILBID) mass spectrometry, we study the self-assembly of purified F-1 subunits in different environments under non-denaturing conditions. We report assembly requirements and identify important assembly intermediates in vitro and in cellula. Our data provide evidence that nucleotide binding is crucial for in vitro F-1 assembly, whereas ATP hydrolysis appears to be less critical. We correlate our results with activity measurements and propose a model for the assembly pathway of a functional F-1 complex. ATPases are the macromolecular machines for cellular energy production. Here the authors investigate factors that govern the assembly of the F-1 complex from a bacterial F-type ATPase and relate differences in activity of complexes assembled in cells and in vitro to structural changes.

Automated summary

The study investigates the assembly process of F-1 complex from Acetobacterium woodii using laser induced liquid bead ion desorption mass spectrometry. The results indicate that nucleotide binding is crucial for in vitro assembly of F-1, while ATP hydrolysis is less critical. The study also proposes a model for the assembly pathway of a functional F-1 complex, correlating the results with activity measurements.