Physical and Biological Chemistry
Phone: (215) 573-7539
Fax: (215) 898-6242
Research Group Website: http://www.sas.upenn.edu/~baumgart/
Starfish vesicle with two coexisting fluid phases (shown in red and blue) that redistribute between regions of high and small curvature. Bar: 5ï¿½m
Research in the Baumgart group is largely centered on the physical chemistry of amphiphile membranes with lateral heterogeneity resulting from non-ideal mixing. Our aims include characterization of biologically relevant membranes including lipids and proteins, where we investigate both composition and shape (curvature) heterogeneity. Both of these aspects are thought to be highly relevant to the function of biological membranes. We focus on freely suspended, rather than solid supported membranes, with an emphasis on bilayer membranes, but we also include monolayer systems. We investigate membranes that laterally segregate into co-existing fluid phases, and are particularly interested in quantitatively understanding the phenomenon of line tension at the phase boundary. We also examine molecular details that govern the partitioning of functionally relevant protein constructs between coexisting membrane phases and thereby aim to contribute to enhancing the biophysical understanding of transmembrane signal transduction, particularly in immune cells such as T-cells, B-cells and mast cells. Our research on aspects of membrane shape is directed at understanding how molecules sort in membrane curvature gradients. This curvature sorting likely contributes substantially to intracellular membrane sorting and trafficking. Furthermore we have recently begun to investigate phase coexistence in binary mixtures of amphiphilic di-block copolymers. Finally, we develop methods to pattern cellular signaling ligands, such as antibodies and adhesion molecules, on pattern scales both above and below optical resolution.
Education and Academic History
- Diploma from the University of Clausthal, Germany, 1998
- PhD from the Johannes Gutenberg University of Mainz, 2001
- Postdoctoral associate at Cornell University (2001 - 2005)
- ERASMUS fellowship (1996 - 1997)
- Fritz ter Meer fellowship, Bayer Company (1997 - 1998)
- Procter & Gamble award for diploma in Chemistry (2001)
- Fellowship from a Graduiertenkolleg of the
- German research foundation, DFG, 1998 - 2001
- Postdoctoral Fellowship from the Keck foundation (2001 - 2004)
Selected Publications31) Heinrich, M., Tian A.,Esposito C., Baumgart T. (2010). Dynamic sorting of lipids and proteins by membrane curvature: a moving phase boundary problem. Proceedings of the National Academy of Sciences. In Print.
30) Johnson, S., Stinson, B., Reminik, J., Go, M., Fang, X., & Baumgart, T. (2010). Temperature dependent phase behavior and protein partitioning in giant plasma membrane vesicles. Biochimica et Biophysica Acta - Biomembranes. In Print.
29) Capraro, B. R., Yoon, Y., Cho, W., Baumgart, T. (2010). Curvature sensing by the epsin N-terminal homology (ENTH) domain measured on cylindrical lipid membrane tethers. Journal of the American Chemical Society, 132 (4), 1200-1201.
28) Levental, I., Byfield, F. J., Choudhourie, P., Madara, J., Gai, F., Baumgart, T., & Janmey P. A. (2009). Cholesterol-dependent phase separation in cell-derived giant plasma membrane vesicles. Biochemical Journal, 424 (2), 163-167.
27) Baker, R. G., Hsu, C. J., Lee, D., Jordan, M. S., Maltzman, J. S., Hammer, D. A., Baumgart, T., & Koretzky, G. A. (2009). The adapter protein SLP-76 mediates “outside-in” integrin signaling and function in T cells. Molecular and Cellular Biology, 29 (20), 5578-5589.
26) Christian, D., Tian, A., Ellenbroek, W., Levental, I., Rajagopal, K., Janmey, P., Liu, A., Baumgart, T., & Discher, D. (2009). Spotted vesicles, striped micelles and Janus assemblies induced by ligand binding. Nature Materials, 8, 843-849. DOI
25) Oh, H., Mohler III, E. R., Tian, A., Baumgart, T., & Diamond, S. L. (2009). Membrane cholesterol is a biomechanical regulator of neutrophil adhesion. Arteriosclerosis, Thrombosis, and Vascular Biology, 29, 1290-1297.
24) Tian, A., Capraro, B. R., Esposito, C., & Baumgart, T. (2009). Bending stiffness depends on curvature of ternary lipid mixture tubular membranes. Biophysical Journal, 97 (6), 1636-1646.
23) Das SL, Jenkins JT, Baumgart T. "Neck geometry and shape transitions in vesicles with co-existing fluid phases: Role of Gaussian curvature stiffness versus spontaneous curvature." Europhysics Letters, 2009, 86, 48003-48008.
22) Tian, A. and Baumgart, T. "Sorting of lipids and proteins in membrane curvature gradients." Biophysical Journal, 2009, 96, 2676-2688.
21) Das S., Tian A., Baumgart T., "Mechanical stability of micropipette aspirated giant vesicles with fluid phase coexistence." Journal of Physical Chemistry, B 2008, 112, 11625-11630.
20) Heinrich M.C., Levental I., Gelman H., Janmey P.A., Baumgart T. "Critical exponents for line tension and dipole density difference from lipid monolayer domain boundary fluctuations." Journal of Physical Chemistry, B 2008, 112, 8063-8068.
19) Esposito C., Tian A., Melamed S., Johnson C., Tee S.-Y., Baumgart T., "Flicker spectroscopy of thermal lipid bilayer domain boundary fluctuations." Biophysical Journal, 2007, 93, 3169-3181.
18) Hess S., Gudheti M., Mlodzianoski M., Baumgart T. "Shape analysis of giant vesicles with fluid phase coexistence by laser scanning microscopy to determine curvature, bending elasticity and line tension." Methods in Molecular Biology, 2007, 400, 367-387.
17) Tian, A., C. Johnson, W. Wang and T. Baumgart. "Line Tension at Fluid Membrane Domain Boundaries Measured by Micropipette Aspiration." Physical Review Letters, 2007, 98, 208102.
16) Wu M., Baumgart T., Hammond S., Holowka D., Baird B., "Differential targeting of secretory lysosomes and recycling endosomes in mast cells revealed by patterned antigen." Journal of Cell Science, 2007, 120, 3147-3154.
15) Baumgart, T., Hunt G., Farkas E., Webb W., Feigenson F., "Fluorescence probe partitioning between Lo / Ld phases in lipid membranes." Biochimica et Biophysica Acta, 2007, 1768, 2182-2194.
14) Baumgart, T., Hammond, A.; Sengupta, P.; Hess, S.; Holowka, D.; Baird, B.; Webb, W.W. "Large-Scale Fluid/Fluid Phase Separation of Proteins and Lipids in Giant Plasma Membrane Vesicles." PNAS, 2007, 104, 3165-3170.
13) Baumgart T., Das, S., Webb, W.W., Jenkins, JT. "Membrane Elasticity in Giant Vesicles with Fluid Phase Coexistence." Biophysical Journal 2005, 89 (2), 1067-1080.
12) Hammond, A.T., Heberle, F.A., Baumgart, T., Holowka, D., Baird, B., Feigenson, G.W. "Crosslinking a Lipid Raft Component Triggers Liquid Ordered-Liquid Disordered Phase Separation in Model Plasma Membranes." Proceedings of the National Academy of Sciences of the United States of America 2005, 102 (18), 6320-6325.
11) Korlach, J., Baumgart, T., Feigenson, G.W., Webb, W.W. "Detection of Motional Heterogeneities in Lipid Bilayer Membranes by Dual Probe Fluorescence Correlation Spectroscopy." Biochimica et Biophysica Acta, 2005, 1668, 158-163.
10) Baumgart, T., Hess, S.T., Webb, W.W., "Imaging Coexisting Fluid Domains in Biomembrane Models Coupling Curvature and Line Tension." Nature 2003, 425, 821-824.