Senior Professor at the LIMES Institute of the University of Bonn
Prof. Dr. U. Benjamin Kaupp
Emeritus Director Molecular Sensory Systems
center of advanced european studies and research (caesar)
an associate of the Max Planck Society
+49 (0)228 9656-100 Office
+49 (0)228 9656-273 Secretary
photo caesar building (on the left): Dr. Corinna Bernsdorff, caesar
Our research group is investigating signal processing in cells. We want to understand how cells detect stimuli and convert them into a physiological response. Cellular signal conversion is a fascinating field of research in which many scientists worldwide are working. A profound understanding of this complex question requires the use of the most modern biological, chemical and physical techniques. That is why biologists, chemists and physicists work closely together in our group.
In particular, we investigate the signal conversion into sensory cells and sperm. Visual cells in the retina of the eye generate an electrical signal using a chain of biochemical reactions. Smelling cells also react to fragrances with an electrical signal. We want to elucidate the molecular mechanisms of signal conversion, in particular the structure, interaction and function of signal proteins. We are particularly interested in receptors, ion channels and transporters. The receptors include the visual pigment rhodopsin and chemoreceptors; the ion channels include the cyclic nucleotide-controlled (CNG) channels from photoreceptors and the pacemaker channels (HCN channels) in the heart and brain; the transporters include the sodium/proton exchanger.
The success of fertilization depends on whether sperm find the egg. Sperm swim with the help of a flagellum. On their way to the egg, they are oriented towards chemical attractants (chemotaxis) or physical stimuli, such as temperature differences in the fallopian tube (thermotaxis) or flow velocities in the surrounding environment (rheotaxis). The "sensory organ" with which sperm register stimuli is mainly the sperm tail, which also serves as a rudder with which they navigate. Although attractants are registered by similar mechanisms as fragrances or light in olfactory or photoreceptor cells, sperm use special signalling molecules that do not occur in other cells. These molecules look, in passing, like old acquaintances known from sensory or heart cells or neurons. However, they have completely different properties and serve other physiological functions. We investigate the cellular signalling pathways and proteins in sperm of sea urchins, zebrafish, salmon, herring, eel, mice and humans.
Finally, we develop optical switches that are used for photonic control of receptors and ion channels. These are "Trojan horses" that are introduced into the cell and release signalling molecules inside the cell with the aid of light. With the help of these Trojan horses, the cellular signal conversion can be precisely tracked in time and space. These so-called caged compounds in combination with fast mixing and quenching techniques are also used to track conformational changes in proteins in time and space.
A panoply of biophysical techniques are employed, including various optical imaging techniques (TIRF, STORM, 2P-microscopy), patch-clamp techniques, electron microscopy and tomography, and microsecond freeze-hyperquenching (MHQ) for time-resolved double-electron-electron resonance (DEER) – to name a few. Another emphasis is on the development of various chemical tools, including fluorescent ligands, caged compounds, and novel photo-affinity labels.
5 selected publications
Jikeli, J. F., Alvarez, L., Friedrich, B. M., Wilson, L. G., Pascal, R., Colin, R., Pichlo, M., Rennhack, A., Brenker, C. & Kaupp, U. B. (2015) "Sperm navigation along helical paths in 3D chemoattractant landscapes" Nat. Commun. 6, 7985
Strünker, T., Goodwin, N., Brenker, C., Kashikar, N. D., Weyand, I., Seifert, R. & Kaupp, U. B. (2011) "The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm" Nature 471, 382-386
Kaupp, U. B., Solzin, J., Hildebrand, E., Brown, J. E., Helbig, A., Hagen, V., Beyermann, M., Pampaloni, F. & Weyand, I. (2003) "The signal flow and motor response controling chemotaxis of sea urchin sperm" Nat. Cell Biol. 5, 109-117
Gauss, R., Seifert, R. & Kaupp, U. B. (1998) "Molecular identification of a hyperpolarization-activated channel in sea urchin sperm" Nature 393, 583-587
Kaupp, U. B., Niidome, T., Tanabe, T., Terada, S., Bönigk, W., Stühmer, W., Cook, N. J., Kangawa, K., Matsuo, H., Hirose, T., Miyata, T. & Numa, S. (1989) "Primary structure and functional expression from complementary DNA of the rod photoreceptor cyclic GMP-gated channel" Nature 342, 762-766