Around thirty per cent of all cellular proteins are located in or on a biological membrane. Numerous diseases are associated with defects in these proteins. It is estimated that around 50 per cent of all drugs developed by the pharmaceutical industry in the future will target the different membranes of cells. However it is quite difficult to biochemically investigate biological membranes. These are the many reasons why many research groups and biotechnology companies are looking closely at cellular membranes.
We are fortunate to have membranes; they separate the interior of cells from the exterior and ensure that precious substances do not leave the cell and toxic substances cannot enter. Membrane proteins do an amazing job in transporting substances from one side of the membrane to the other. This process occurs in bacteria and in humans in much the same way. Prof. Dr. Hans-Georg Koch and his team at the Institute for Biochemistry and Molecular Biology at the University of Freiburg have found out how transport channels are formed and how proteins are integrated into the membrane by way of auxiliary components.
COPI vesicles, one of the three major types of intracellular transport vesicles, are an excellent example of how the molecular analysis of individual vesicle components can lead to an understanding of the biogenesis and transport mechanisms of membrane vesicles as a whole. The research carried out by Dr. Felix T. Wieland’s team at the University of Heidelberg has made a decisive contribution to such detailed insights.
Dr. Uwe Schulte of the Freiburg-based biotech company Logopharm GmbH is a specialist in the analysis of membrane proteins membrane protein complexes and functional networks involving membrane proteins. In an interview with BIOPRO Schulte expresses his views on the direction research should take.
Prof. Dr. Irmgard Sinning, biochemist and structural biologist at the University of Heidelberg, will be awarded the 2014 Leibniz Prize from the German Research Foundation (DFG) for her work on the structure and function of complexes that transport different membrane proteins to the correct cellular compartments in the appropriate target membranes. Her research is primarily focussed on the co-translational SRP pathway mediated by signal recognition particles and on the GET pathway, which ensures the post-translational insertion of membrane proteins.
Far from being isolated units cells constantly interact with their environment, exchanging substances and information. Such interaction is possible thanks to proteins that are gated across the cell membrane out of the cell and proteins that are integrated in the cell membrane, such as receptors. A research group led by Dr. Hans-Georg Koch from the University of Freiburg focuses on transport mechanisms in bacteria that have developed smart mechanisms to transport proteins across the cell membrane.
The cellular protein machinery is a marvel of nature and produces umpteen different proteins. Most of these proteins pass through a stack of membrane-enclosed discs, known as the Golgi apparatus, a miniature reaction chamber where the finishing touch is progressively added to the proteins. Rudolf Hausmann, professor and head of the Department of Bioprocess Engineering at the University of Hohenheim, is developing membranes based on the Golgi model to facilitate production of proteins outside the cells.
The majority of research groups around the world working on membrane receptors are concentrating on the interactions between the receptors and the signalling molecules in the interior of cells and each individual receptor tends to be seen as a black box. The independent research group led by junior professor Dr. Maximilian Ulbrich of the BIOSS excellence cluster at the University of Freiburg has developed a high-resolution real-time method for looking at individual membrane-bound receptors.
The powerhouses of cells are surprisingly dependent on external help. More than ninety per cent of all proteins required by the mitochondria are produced outside the outer mitochondrial membrane. How are these proteins transported across the membrane and how do they find their way into the mitochondria? A group of researchers led by Prof. Dr. Chris Meisinger at the University of Freiburg has been investigating the role of large protein complexes in the outer mitochondrial membrane for many years.
For chemists cellular biomembranes are hard nuts to crack. It is difficult to analyze proteins that are firmly anchored in biomembranes using standard biochemical methods and it is even more difficult to investigate their three-dimensional structure and interaction with other proteins. A group of researchers led by Prof. Dr. Anne S. Ulrich at the Karlsruhe Institute of Technology KIT have developed a method that enables them to take a close look at individual atoms and even at the atoms natural environment in the lipid bilayer.
The Heidelberg virologist Hans-Georg Kräusslich and his team are exploring the molecular architecture and morphogenesis of the HI-Virus and the processes occurring at the plasma membrane of the host cell that lead to the release of new viruses and new infections. The budding and maturation processes of HIV particles and the lipid composition of their envelope could be used as targets for the development of new drugs to combat AIDS.
Mitochondria contain an intertwined membrane system that is necessary for the production of energy. Errors in the inner mitochondrial membrane architecture prevent energy from being produced. A group of researchers led by Dr. Martin van der Laan at the University of Freiburg in cooperation with partners has identified a protein complex that plays a key role in the architecture and functioning of the mitochondria.
Proteins are the active part of cells. They recognise sequences transport nutrients and information as well as getting rid of waste. Proteins that go from one side of a membrane through to the other serve as transporters and channels and help molecules across membranes. Dr. Thomas Becker and his colleagues from the Institute for Biochemistry and Molecular Biology at the University of Freiburg are studying these complex processes. They are particularly interested in how transmembrane proteins are integrated into the mitochondrial membranes of yeast cells the protein complexes involved and whether the lipid composition of the membranes plays a role in this process.
The planar cell polarity is crucial for example in the development of ordered organ structures. One of the issues being investigated by researchers led by Prof. Dr. Matias Simons from the University of Freiburg is how the perfectly ordered patterns on the surface of Drosophila wings develop.
Cholesterol has been demonised for a long time as high cholesterol levels are seen as major risk factors for atherosclerosis myocardial infarction and gallstones. However cholesterol is an essential component of mammalian cell membranes and is required for proper membrane function. It exists in huge quantities in the human body. In addition to being essential for cell survival and hence all animal life in general cholesterol also plays a crucial role in the production of specific immune responses as Prof. Dr. Wolfgang Schamel from the Institute of Biology III and the Centre for Chronic Immunodeficiency CCI and Prof. Dr. Rolf Schubert from the Department of Pharmaceutical Technology at the University of Freiburg have shown.
Yersinia enterocolitica, a pathogenic bacterium, causes fever and diarrhea. By help of a protein anchored in its membrane, Yersinia attaches to its host cells and infects them. Scientists of the Max Planck Institute for Developmental Biology in Tübingen and the Leibniz-Institut fuer Molekulare Pharmakologie in Berlin have determined the structure of an important component of the membrane protein and have gained insight into its biogenesis. The membrane proteins provide an interesting starting point for the development of new antibiotics against pathogens.
Humans bacteria and plants possess ammonium transport proteins that transport nitrogen into cells. Crystallographic investigations have led to the elucidation of the complex structure of numerous ammonium transporters. However little is known about the complex signalling cascades and the function of the transport proteins. Dr. Andrade and her team are taking a very close look at these transport molecules.
Although they are present almost everywhere, on land and sea, a group of related bacteria in the superphylum Planctomycetes-Verrucomicrobia-Chlamydiae, or PVC, have remained in relative obscurity ever since they were first described about a decade ago. Scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have discovered that these poorly-studied bacteria possess proteins thought to exist only in eukaryotes – organisms whose cells have a nucleus. Their findings, featured on the cover of today’s edition of PLoS Biology, could help to unravel part of the evolutionary history of eukaryotic cells such as our own.
Viscofan BioEngineering is the first company to market cell culture inserts for the cultivation of cells and tissues that are entirely made from collagen. In contrast to traditional PTFE membranes, Viscofan´s cell culture inserts do not need to be coated with collagen prior to use. The new collagen inserts are extremely suitable for the cultivation of adherent primary cells such as cardiomyocytes, neurons, fibroblasts, cell lines, stem cells as well as facilitating the formation of tissue structures.
The proteins of the cadherin family form a kind of molecular zip that binds cells closely together thereby preventing cancer cells from migrating for example. Prof. Dr. Doris Wedlich and her team from the Karlsruhe Institute of Technology KIT were involved in the discovery that cadherins are not only involved in cell adhesion but also have other functions.
Modern methods used for the production of nitrogen for use in plant fertilisers and other applications are very efficient. Prof. Dr. Oliver Einsle and his team at the University of Freiburg have found a way to investigate the reactive centres of bacterial enzymes. All nitrogen-converting enzymes contain metal ions and it is these metal ions that mediate the underlying chemical reactions.
For a long time researchers believed that cells more or less invite Trojan Horses to invade them and this is what standard textbooks say. This all changed when Dr. Winfried Römer showed during his postdoctoral period what really happened when toxins invade cells. This has led to new ways of looking at the processes associated with intoxication and the infection of human cells with viruses and bacteria. Today junior professor Dr. Winfried Römer is investigating the mechanisms in greater detail at the University of Freiburg.
Waltraud Schulze is like the plants she studies: a master in the art of living and extremely diverse. For her explorations by bike, the biologist loves the arctic cold of Lake Baikal as much as the desert heat of Australia. She is considered to be the first woman to have climbed three 6,000 m summits in the Tibetan Plateau, she writes travel guides, runs her own website and has recently started learning Chinese. Since November 2012, Schulze has been chair of the new Department of Plant Systems Biology at the University of Hohenheim in Stuttgart.
Apoptotic processes, i.e. cell death mediated by intracellular programmes, have been implicated in a variety of diseases. Apoptotic processes eliminate superfluous or irreparably damaged cells from the body; however, defective apoptotic processes harm the organism. New research results show that processes at the mitochondrial membrane might be excellent targets for pharmaceutical interference with apoptosis.
The skin creates a barrier between the body and its environment. Natural antibiotics that can kill potential pathogens such as bacteria or fungi represent an additional level of protection by the immune system. Dermcidin one such antibiotic produced in human sweat glands is active against a number of microorganisms on the skin. A team of scientists from the University Hospital Tübingen and the Max Planck Institute for Developmental Biology were part of a collaborative effort that has uncovered evidence for a novel mechanism of action of dermcidin in the harsh environment of sweat.