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Publication Abstract from PubMed

The F(1) domain of F(o)F(1)-ATP synthases/ATPases (F(o)F(1)) possesses three catalytic sites on the three alphabeta interfaces, termed alpha(E)beta(E), alpha(D)beta(D), and alpha(T)beta(T), located mainly on the beta subunits. The enzyme also has three non-catalytic ATP-binding sites on the three alphabeta interfaces, located mainly on the alpha subunits. When ATP does not bind to the non-catalytic site, F(o)F(1) becomes significantly prone to ADP inhibition, ultimately resulting in the loss of ATPase activity. However, the underlying mechanism of ADP inhibition remains unclear. Here, we report the cryo-EM structure of the non-catalytic site-depleted (DeltaNC) F(o)F(1) from thermophilic Bacillus sp. PS-3, which completely lacks the ability to bind ATP (and ADP) upon transitioning to the ADP-inhibited form. The structure closely resembled the 81 degrees rotated structure of the wild-type F(o)F(1), except for minor movements in the C-terminal region of the alpha subunit. In this structure, unlike the wild-type enzyme, the catalytic site at alpha(D)beta(D), responsible for ATP hydrolysis, was occupied by ADP-Mg, with the absence of Pi. Furthermore, the catalytic site at alpha(E)beta(E), where ATP enters the F(1) domain during steady-state catalysis, is occupied by ADP, seemingly impeding further ATP binding to the enzyme. The structure suggests that the ADP-inhibited form of the F(1) domain is more likely due to differences in the nucleotide-binding states at the catalytic sites rather than structural differences.

ADP-inhibited structure of non-catalytic site-depleted F(o)F(1)-ATPase from thermophilic Bacillus sp. PS-3.,Kobayashi R, Nakano A, Mitsuoka K, Yokoyama K Biochim Biophys Acta Bioenerg. 2025 Apr 1;1866(2):149536. doi: , 10.1016/j.bbabio.2025.149536. Epub 2025 Jan 7. PMID:39788275^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.