Function and dynamics of P4 ATPases in vesicular transport
Final Report Abstract
P-type ATPases in subfamily IV (P4-ATPases) are transmembrane proteins unique for eukaryotes. Accumulating evidence shows that P4-ATPases catalyze phospholipid transport across cellular membranes, a process likely to be the initial event in vesicle budding in the secretory pathway. However, our understanding of lipid translocation, vesiculation and the involvement of P4-ATPases in these processes is just beginning to emerge. In this project we identified of a novel mouse P4-ATPase that serves an essential role in maintaining Golgi morphology and secretory function in immune cells, provided evidence for a critical role of a human P4-ATPase in the apical membrane organization of polarized cells, and contributed to the characterization of a new protein family that act as subunits for P4-ATPases. For a detailed molecular analysis we establish a purification and reconstitution procedure for these pumps in complex with their subunits into lipid vesicles. This model system allows for a more flexible choice of biochemical, biophysical and microscopy techniques for characterizing the role of these proteins in vesicular budding. Collectively, these studies have contributed significantly to our understanding of the molecular and physiological function of a protein family that evolved as a basis for the secretory pathway of eukaryotes.
Publications
- (2009). Identification of a novel mouse P4-ATPase family member highly expressed during spermatogenesis. Journal Cell Science 122, 2866-2876
Xua, P., Okkeri, J., Hanisch, S., Hua, R.-Y., Xua Q., Pomorski, T.G., Ding, X.-Y.
- (2010) Intracellular targeting signals and lipid specificity determinants of the ALA/ALIS P4-ATPase complex reside in the catalytic ALA alpha-subunit. Mol Biol Cell. 21, 791- 801
López-Marqués, R.L., Poulsen, L.R., Hanisch, S., Meffert, K., Buch-Pedersen, M.J., Jakobsen, M.K., Pomorski, T.G., Palmgren, M.G.
- (2010). A flippase-independent function of ATP8B1, the protein affected in familial intrahepatic cholestasis type 1, is required for apical protein expression and microvillus formation in polarized epithelial cells. Hepatology 51, 2049-2060
Verhulst, P.M., van der Velden, L.M., Oorschot, V., van Faassen, E.E., Klumperman, J., Houwen, R.H.J., Pomorski, T.G., Holthuis, J.C.M., Klomp, L.W.J.
- (2011). Pumping lipids with P4-ATPases. Biol. Chem. 392, 67-76
Lopez-Marques, R.J., Holthuis, J.C.M. and Pomorski, T.G.
- (2013) P4-ATPases: lipid flippases in cell membranes. Pflugers Arch
Lopez-Marques, R.L., Theorin, L., Palmgren, M.G., Pomorski, T.G.
- (2014) Structure and mechanism of ATP-dependent phospholipid transporters. Biochim Biophys Acta. Pii S0304-4165(14)00141-X
López-Marqués, R.L., Poulsen, L.R., Bailly, A., Geisler, M., Pomorski, T.G., Palmgren, M.G.
(See online at https://doi.org/10.1016/j.bbagen.2014.04.008) - A phospholipid uptake system in the model plant Arabidopsis thaliana. Nature Communications volume 6, Article number: 7649 (2015), 14 S.
Poulsen, L.R., López-Marqués, Pai R. Pedas, Stephen C. McDowell, Elizabeth Brown, R.L., Harper, J.F., Kunze, R., Palmgren, M.G. and Günther Pomorski, T.
(See online at https://doi.org/10.1038/ncomms8649)
