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HALOmem is an interdisciplinary research center at the Martin Luther University Halle-Wittenberg (MLU). We focus on the structure of membrane proteins and their interactions with the surrounding membrane. HALOmem was founded as a joint effort of the Institute of Biochemistry & Biotechnology (Faculty of Natural Sciences I) and the Institutes of Physics and Chemistry (Faculty of Natural Sciences II). The research center brings together resources and special expertise from those institutes, such as recombinant protein production, biophysical methods for studying membranes, and protein structure determination by mass spectrometry, cryo-electron microscopy, crystallography and NMR. Within the first phase of funding of the HALOmem research center (2009-2015), two independent tenure-track junior research groups were established:

• Research Group I: Membrane Protein Biochemistry (Dr. Mikio Tanabe)
• Research Group II: Biophysical Chemistry of Membranes (Prof. Dr. Kirsten Bacia)

Within the newly started phase of funding of HALOmem two additional independent tenure-track junior research groups joined:

• Research Group III: Cryo-Electron Microscopy of Membrane Complexes (Jun.-Prof. Panagiotis L. Kastritis)
• Research Group IV: Biophysical Characterisation of Medically Relevant Proteins (Jun.-Prof. Dr. Carla Schmidt)

Scientific Aims

Why membrane proteins?
Membrane proteins represent almost a quarter of all proteins within living cells. They direct and regulate a wide range of essential functions, being responsible for such diverse process as inter- and intracellular communication, transport of nutrients and generation of energy. Their vital nature is reflected by the fact that up to 70% of current drug targets are membrane proteins. For G-Protein Coupled Receptors, for instance, this represents a multi-billion dollar market. Despite their obvious pharmaceutical importance, our understanding of membrane protein function at an atomic level remains rudimentary. Detailed information about the spatial structure – a prerequisite for modern rational drug design – is rare for membrane proteins.

The key to structure determination of membrane proteins is the production and purification of sufficient quantities of functional protein.

The most critical point requires the correct three-dimensional architecture of proteins within their natural environment – which is the biological membrane. During the first funding period Research Group I (Dr. Mikio Tanabe) established skills for membrane protein preparation in high quantity and quality. Research Group II (Prof. Dr. Kirsten Bacia) developed methods for reconstitution of membrane proteins into suitable environments. The interplay of optimised protein and membrane characteristics succeeded in the production of fully functional membrane proteins.

However, membrane proteins are often part of macromolecular complexes. This is not only academically relevant but in fact, the pharmacological interaction of a potential therapeutic agent depends on whether its target is isolated or part of a molecular complex. Therefore, the characterisation of membrane protein complexes is the scientific direction of ZIK HALOmem II towards academic and applied research.

Our Aims

Synergies between the analytically as well as between the biochemically and physico-chemically working groups will be used to pursue a medically relevant (in vivo) and an experimentally accessible (in vitro) approach. Therefore, scientific research now focusses on understanding and treatment of diseases based on malfunction of membrane proteins. The extended strategy paper of HALOmem II guarantees the continuation of ZIK HALOmem as a powerful and effective instrument at the Martin Luther University Halle-Wittenberg for analysing the structure and dynamic of membrane proteins and their complexes.

Scientific research at HALOmem has led to the acquisition of a high resolution cryo-electron microscope (novel in Halle) to enhance structure determination of biomolecules. Research Group III uses this technology to analyse the structure of membrane protein complexes.

Research Group IV analyses the structural biology of membrane proteins in the context of diagnosis and/or therapy. Here, the research focus is on the structural determination of membrane complexes in synaptic vesicles and in the neuronal synapse.

HALOmem is supported by the federal Zentrum für Innovationskompetenz (ZIK, Center for Innovation Competence) initiative of the Bundesministerium für Bildung und Forschung (BMBF) and by the European Regional Development Fund of the state Sachsen-Anhalt.