Membranes

Model membranes and their interaction with small molecules and peptides

We are interested in the structure and dynamics of lipid bilayers as models for cell membranes, their domain structure, and the interaction of small molecules with these bilayers. To this end, we investigate lipid membranes in the presence of a broad range of very different molecules like sterols (especially cholesterol and its derivatives), small hormones (such as estradiol), ceramides, small peptides (neuropeptide Y or ghrelin), drugs (for instance anesthetics, small-molecule kinase inhibitors), or others.

Using a broad variety of different NMR techniques and other methods (fluorescence, DSC, molecular dynamics simulations), we study the influence of these molecules on lipid membranes as well as their binding, localization, orientation, and dynamic behavior in the membrane. The obtained information will help to understand the interactions of such molecules with cell membranes and therefore help to improve the action of medically relevant molecules.

Collaborations:

Dr. Peter Müller, Humboldt-Universität Berlin

 

Publications:

Hilsch, M., Haralampiev, I. Müller, P., Huster, D., Scheidt, H.A.
Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism.
Beilstein J. Org. Chem. (2017), in press.

Vogel, A., Scheidt, H.A., Baek, D.J., Bittman, R., Huster, D.
Structure and dynamics of the aliphatic cholesterol side chain in membranes as studied by 2H NMR spectroscopy and molecular dynamics simulation.
Phys. Chem. Chem. Phys. 18 (2016) 3730-3738.

Scheidt, H.A., Haralampiev, I., Theisgen, S., Schirbel, A., Sbiera, S., Huster, D., Kroiss, M., Müller, P.
The adrenal specific toxicant mitotane directly interacts with lipid membranes and alters membrane properties depending on lipid composition.
Mol. Cell. Endocrinol. 428 (2016) 68-81.

Haralampiev, I. , Scheidt, H.A., Abel, T., Luckner, M., Herrmann, A., Huster, D., Müller, P.
The interaction of sorafenib and regorafenib with membranes is modulated by their lipid composition.
Biochim. Biphys. Acta 1858 (2016) 2871-2881.

Scheidt, H.A., Klingler, J., Huster, D., Keller, S.
Structural Thermodynamics of myr-Scr(2-19) binding to phospholipid membranes.
Biophys. J. 109 (2015) 586-694.

Scheidt, H.A., Meyer, T., Nikolaus, J., Baek D.J., Haralampiev, I., Thomas, L., Bittman, R., Müller, P., Herrmann, A., Huster, D.
Cholesterol’s aliphatic side chain modulates membrane properties.
Angew. Chemie Int. Ed. 52 (2013) 12848-12851.

Dynamics of transmembrane helices that are substrates for intramembrane proteases

Intramembrane proteases are cleavage enzymes, which reside in the cell membrane. In contrast to soluble proteases, the mechanism that governs the recognition of substrates for intramembrane proteases is not understood. The goal in this project is to investigate the molecular basis for the target recognition of intramembrane proteases. We hypothesize that there is connection between substrate dynamics and the recognition by the respective intramembrane protease. Therefore, we investigate the local dynamics of known substrates of the intramembrane protease γ-secretase and introduce mutations that change the dynamics of these helices.

For this purpose, we prepare the transmembrane domain of the substrate in different lipid-bilayer systems and measure the local flexibility of the transmembrane domain at certain points. This is realized by various kinds of solid-state NMR spectroscopy methods. With these methods, we investigate the influence of mutations in the transmembrane domain of substrates and the influence of the lipid environment on the dynamic behavior of the substrates. Close collaboration with other colleagues enables us to correlate these results with molecular dynamics simulations and changes in the cleavage behavior of the intramembrane protease. This will provide a deeper insight in the rules which determine these processes on a molecular level.

Collaborations:

  • Dr. Christina Scharnagl, Technische Universität München
  • Prof. Dr. Harald Steiner, Ludwig-Maximilians-Universität München
  • Prof. Dr. Dieter Langosch, Technische Universität München

Publications:

Penk, A., Müller, M., Scheidt, H.A., Langosch, D., Huster D.
Structure and Dynamics of the Lipid Modifications of a Transmembrane α-Helical Peptide Determined by 2H Solid-State NMR Spectroscopy.
Biochim. Biophys. Acta (Biomembranes) 1808 (2011) 784-791

A new model for the interpretation of transmembrane helix dynamics

In our research, we often work with single membrane-spanning helices. To investigate their dynamics DIPSHIFT order parameters are measured routinely, but the interpretation remains difficult. To aid the interpretation of the NMR results, we are currently establishing a new model derived from the GALA (geometric analysis of labeled alanines) model from literature. The experimental input of this model are 2H NMR order parameters of labeled alanines in the peptide that are measured in oriented samples. The interpretation of these order parameters is achieved by a geometrical model, in which the orientation of the helix is described by a tilt and an azimuth angle and, depending on the exact implementation, sometimes by additional distribution widths of these angles.

In our work we are now aiming to extend this model to also work for DIPSHIFT order parameters measured for unoriented samples under magic angle spinning. The main advantage of this approach is that the labeled positions are not restricted to alanine, which is why it works for a much wider range of peptide sequences, and the complicated preparation of oriented samples can be avoided. Furthermore, several order parameters can be measured with one sample, thereby significantly reducing the number of required peptides with different labeling schemes.

Collaborations:

Dr. Christina Scharnagl, Technische Universität München

Publications:

in preparation

Structure of stratum corneum lipid model membranes

The stratum corneum is the outermost layer of the skin. It protects the organism against pathogens and prevents dehydration. Its barrier function is achieved by membranes mainly formed from ceramides (often with very long hydrocarbon chains), free fatty acids, and cholesterol at about equimolar ratio. Despite the importance of this barrier, its basic structure and the influence of ceramide classes and chain lengths on its properties are still poorly understood. Therefore, we investigate a number of model systems, where we exchange different ceramides or vary their chain length to obtain information on the basic physical properties of the model membranes. To reach this goal, we employ solid-state 2H NMR spectroscopy and closely collaborate with groups using neutron scattering and synthesizing the molecules with various labeling schemes.

Collaborations:

  • Prof. Dr. Dr. Reinhard Neubert, Martin-Luther-Universität Halle-Wittenberg
  • Prof. Dr. Bodo Dobner, Martin-Luther-Universität Halle-Wittenberg
  • Dr. Thomas Hauss, Helmholtz-Zentrum Berlin
  • Dr. Gerald Brezesinski, Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Potsdam

Publications:

Schroeter, A., Stahlberg, S., Školová, B., Sonnenberger, S., Eichner, A., Huster, D., Vávrová, K., Hauß, T., Dobner, B., Neubert, R.H.H., Vogel, A.
Phase separation in stratum corneum lipid model membranes based on ceramide [NP]: neutron diffraction and solid-state NMR.
Soft Mat. 13 (2017) 2107-2119.

Eichner, A., Stahlberg, S., Sonnenberger, S., Lange, S., Dobner, B., Ostermann, A., Schrader, T.E., Hauß, T., Schröter, A., Huster, D., Neubert, R.H.H.
Influence of the penetration enhancer isopropyl myristate on stratum corneum lipid model membranes revealed by neutron diffraction and 2H NMR experiments.
Biochim. Biophys. Acta 1859 (2017) 745-755.

Oliveira, J.S.L., Lange, S., Dobner, B., Brezesinski, G.
The effect of non-deuterated and deuterated isopropyl myristate on the thermodynamical and structural behavior of a 2D stratum corneum model with ceramide [AP].
ChemPhys. Lipids 204 (2017) 1-9.

Stahlberg, S., Lange, S., Dobner, B., Huster, D.
Probing the role of ceramide headgroup polarity in short-chain model skin barrier lipid mixtures by 2H solid-state NMR spectroscopy.
Langmuir 32 (2016) 2023-2031.

Sonnenberger, S., Lange, S., Langner, A., Neubert, R.H.H., Dobner B.
Synthesis of ceramides NS and NP with perdeuterated and specifically ω deuterated N-acyl residues.
J. Labelled Comp. Radiopharm. 59 (2016) 531-542

Stahlberg, S., Školová. B., Madhu, P.K., Vogel, A., Vávrová, K., Huster, D.
Probing the role of ceramide acyl chain length and sphingosine unsaturation in model skin barrier lipid mixtures by 2H solid-state NMR spectroscopy.
Langmuir 31 (2015) 4906-4915.

Školová, B., Hudská, K., Pullmannová, P., Kováčik, A., Palát, K., Roh, J., Fleddermann, J., Estrela-Lopis, I., Vávrová, K.
Different phase behavior and packing of ceramides with long (C16) and very long (C24) acyls in model membranes: infrared spectroscopy using deuterated lipids.
J. Phys. Chem.B, 118 (2014) 10460-10470.

Engelbrecht, T.N., Schroeter, A., Hauß, T., Demé, B., Scheidt, H.A., Huster, D., Neubert, R.H.H.
The impact of ceramides NP and AP on the nanostructure of stratum corneum lipid bilayer. Part I: neutron diffraction and 2H NMR studies on multilamellar models based on ceramides with symmetric alkyl chain length distribution.
Soft Matter 8 (2012) 2599-2607.

Engelbrecht, T., Hauß, T., Süß, K, Vogel, A., Roark, M., Feller, S.E., Neubert, R.H.H., Dobner, B.
Characterisation of a New Ceramide EOS Species: Synthesis and Investigation of the Thermotropic Phase Behaviour and Influence on the Bilayer Architecture of Stratum Corneum Lipid Model Membranes.
Soft Matter 7 (2011) 8998-9011.

letzte Änderung: 05.09.2017