Autoinhibition and regulation by phosphoinositides of ATP8B1, a human lipid flippase associated with intrahepatic cholestatic disorders

Thibaud Dieudonné (1, 2, 3) , Sara Abad Herrera (4) , Michelle Juknaviciute Laursen (2, 3) , Maylis Lejeune (1) , Charlott Stock (2, 3) , Kahina Slimani (1) , Christine Jaxel (1) , Joseph A. Lyons (3) , Cédric Montigny (1) , Thomas Günther Pomorski (4) , Poul Nissen (2, 3) , Guillaume Lenoir (1)

1 I2BC - Institut de Biologie Intégrative de la Cellule
2 DANDRITE - Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin
3 Aarhus University [Aarhus]
4 RUB - Ruhr University Bochum = Ruhr-Universität Bochum

P4-ATPases flip lipids from the exoplasmic to the cytosolic leaflet, thus maintaining lipid asymmetry in eukaryotic cell membranes. Mutations in several human P4-ATPase genes are associated with severe diseases, for example in ATP8B1 causing progressive familial intrahepatic cholestasis, a rare inherited disorder progressing toward liver failure. ATP8B1 forms a binary complex with CDC50A and displays a broad specificity to glycerophospholipids, but regulatory mechanisms are unknown. Here, we report functional studies and the cryo-EM structure of the human lipid flippase ATP8B1-CDC50A at 3.1 Å resolution. We find that ATP8B1 is autoinhibited by its N- and C-terminal tails, which form extensive interactions with the catalytic sites and flexible domain interfaces. Consistently, ATP hydrolysis is unleashed by truncation of the C-terminus, but also requires phosphoinositides, most markedly phosphatidylinositol-3,4,5-phosphate (PI(3,4,5)P 3 ), and removal of both N- and C-termini results in full activation. Restored inhibition of ATP8B1 truncation constructs with a synthetic peptide mimicking the C-terminal segment further suggests molecular communication between N- and C-termini in the autoinhibition and demonstrates that the regulatory mechanism can be interfered with by exogenous compounds. A recurring (G/A)(Y/F)AFS motif of the C-terminal segment suggests that this mechanism is employed widely across P4-ATPase lipid flippases in plasma membrane and endomembranes.

Domaines: Sciences du Vivant [q-bio]

Thibaud Dieudonné, Sara Abad Herrera, Michelle Juknaviciute Laursen, Maylis Lejeune, Charlott Stock, et al.. Autoinhibition and regulation by phosphoinositides of ATP8B1, a human lipid flippase associated with intrahepatic cholestatic disorders. eLife, 2022, 11, pp.e75272. ⟨10.7554/eLife.75272⟩. ⟨hal-03653742⟩