An ATP “Synthase” Derived from a Single Structural Domain ofBacterial Histidine Kinase

ATP (adenosine triphosphate) is a vital energysource for living organisms, and its biosynthesis andprecise concentration regulation often depend on macromolecular machinery composed of protein complexesor complicated multidomain proteins. We have identified a single-domain protein HK853CA derived frombacterial histidine kinases (HK) that can catalyze ATPsynthesis efficiently. Here, we explored the reactionmechanism and multiple factors that influence thiscatalysis through a combination of experimental techniques and molecular simulations. Moreover, we optimized its enzymatic activity and applied it as an ATPreplenishment machinery to other ATP-dependent systems. Our results broaden the understanding of ATPbiosynthesis and show that the single CA domain can beapplied as a new biomolecular catalyst used for ATPsupply.