Biophysik
Final Report Abstract
A number of biophysical methods based on fluorescence spectroscopy, microscopy and electron spin resonance (EPR) were established to analyse the mechanisms underlying protein-mediated translocation of lipids across cellular membranes and their intracellular transport to distinct organelles. A new spin-labelled phospholipid analog was synthesized and characterized in model membranes. The advantage of this analog is that the EPR active reporter group is linked to an unsaturated fatty acyl chain different to saturated phospholipid analogs used so far. The need for those analogs arises from the fact that biological membranes contain unsaturated phospholipids to a large extent. Our biophysical methods were employed to map the dynamics and distribution of phospholipids in various cell types as a step towards the identification of the membrane proteins involved in this process. These studies led to the identification of an ATP-driven phospholipid transporter of the P4-ATPase subfamily that serves an essential role in maintaining Golgi morphology and secretory function in immune cells. A detailed biophysical analysis of the ATP binding cassette transporter ABCA1 revealed a primary function of this transporter in the control of both transversal and lateral lipid distribution at the membrane. In studies on the pathogenic unicellular parasite Leishmania donovani a lipid transporter of the P4-ATPase subfamily was characterized that plays an essential role in maintaining phospholipid asymmetry in the parasite plasma membrane. Finally, we uncovered an evolutionarily conserved lipid interaction domain in a family of lipid binding proteins that is essential for the cellular functions of these proteins in intracellular membrane transport, lipid metabolism, and cell signaling events. Collectively, this knowledge will contribute to our understanding how cells control transbilayer lipid asymmetry in their cellular membranes.
Publications
- (2009) Biophysical characterization of a new phospholipid analogue with a spin-labeled unsaturated fatty acyl chain. Biophysical Journal, Vol. 96. 2009, Issue 3, pp. 1008–1015.
Bunge A, Windeck AK, Pomorski T, Schiller J, Herrmann A, Huster D, Müller P
(See online at https://dx.doi.org/10.1016/j.bpj.2008.10.037) - (2009) Deleted in Liver Cancer 1 (DLC1) activation requires lipid interaction through a polybasic region preceding the RhoGAP domain
Molecular Biology of the Cell, vol. 20. 2009, no. 20, pp. 4400-4411.
Erlmann, P., Schmid, S., Horenkamp, F.A., Geyer, M., Pomorski, T.G., Olayioye, M.A.
(See online at https://dx.doi.org/10.1091/mbc.E09-03-0247) - (2009) Functional implications of the influence of ABCA1 on lipid microenvironment at the plasma membrane: a biophysical study. The FASEB Journal, vol. 23. 2009, no. 6, pp. 1775-1785.
Zarubica A, Plazzo AP, Stöckl M, Trombik T, Hamon Y, Müller P, Pomorski T, Herrmann A, Chimini G
(See online at https://dx.doi.org/10.1096/fj.08-122192) - (2009) Identification of a novel P4-ATPase family member from mice highly expressed during spermatogenesis. Journal of Cell Science, Vol. 122. 2009, pp.2866-2876.
Xu, P., Okkeri, J., Hanisch, S., Hua, R.-Y., Xua, Q., Pomorski, T. and Ding, X.-Y.
(See online at https://dx.doi.org/10.1242/jcs.047423) - (2010) Disruption of the lipid-transporting LdMT-LdRos3 complex in Leishmania donovani affects membrane lipid asymmetry but not host cell invasion. PLoS One 5(8):e12443.
Weingärtner, A., Drobot, B., Herrmann, A., Sánchez-Cañete, M.P., Gamarro, F., Castanys, S., Pomorski, T.G.
(See online at https://dx.doi.org/10.1371/journal.pone.0012443) - (2010). A flippase-independent function of ATP8B1 is required for apical protein expression and microvilli formation in polarized intestinal epithelial cells. Hepatology, Vol. 51. 2010, Issue 6, pp. 2049–2060.
Verhulst, P.M., van der Velden, L.M., Oorschot, V., van Faassen, E.E., Klumperman, J., Houwen, R., Pomorski, T., Klomp, L.W.J. and Joost H.C.M.
(See online at https://dx.doi.org/10.1002/hep.23586) - (2011) Flip or flop: mechanism and (patho)physiology of P4 ATPase-catalysed lipid transport. In: Transmembrane Dynamics of Lipids, ed. Philippe Devaux, Publ.: Wiley
Verhulst, P.M., Pomorski, T., and Holthuis J.C.M.
