What do we do and why do we do it?

Overview toxin effects

Cholesterol-dependent cytolysins

Small GTPase effects of pneumolysin

Our questions

Our methods

Our collaborations

OVERVIEW TOXIN EFFECTS (top)

Evolutionary bacteria have developed adaptive mechanisms to improve their interaction with the host, which in many cases has a negative impact on the host. The existence of bacterial protein toxins represents such an adaptive response.  

CHOLESTEROL-DEPENDENT CYTOLYSINS (top)

The group of cholesterol-dependent cytolysins (CDC) represents several protein toxins with very high pathogenic capacity. 

PREVOIUS WORK OF THE GROUP (top)

We have discovered a macropore-independent small GTPase-activation by sub-lytic amounts of pneumolysin. Treatment of human neuroblastoma cells with pneumolysin leads to activation of RhoA and Rac1 GTPases and formation of stress fibers, lamellipodia and filopodia.  

OUR QUESTIONS (top)

At present, our research interests focus in the following directions:

1. The importance of pore formation in small GTPase activation by CDC and critical domains

2. The molecular mechanisms downstream of membrane cholesterol binding by the toxin and the role of lipid raft reorganization

3. Pneumolysin is a key pathogenic factor in pneumococcal meningitis. Actin and small GTPase activation play an important role in synaptic function of the central nervous system. Since pneumolysin produces massive actin cytoskeleton remodeling and strong small GTPase activation, clarifying its provisional effects on synaptic function represents an important question.  

4. Defining specific molecular targets with relevance towards ameliorating the symptoms of neuronal damage in the course of pneumococcal meningitis.

OUR METHODS (top)

Our laboratory employs multiple experimental approaches to answer our questions. These include:

1. Primary cell cultures and cell lines preparation and transfection

2. Live imaging - confocal microscopy (Leica AOBS SP2, Leica AOBS SP5 microscopes), wide-field fluorescent microscopy (Leica, Zeiss, Olympus setups)

3. STED microscopy

4. Immunohisto- and immunocytochemistry

5. Molecular biology - vector cloning, vector purification, site-directed mutagenesis

6. Protein biochemistry - Western blotting, slot- and dot-blotting, subcellular fractionation

7. Fluorescence activated cell sorting (FACS)

OUR COLLABORATIONS (top)

Good collaborations are an important prerequisite for a productive and effective research work. We are very proud to have the best collaborators ever.

Prof. Dr. Timothy J. Mitchell, University of Glasgow

Prof. Dr. Roland Nau, University of Göttingen

Dr. Annette Spreer, University of Göttingen

Prof. Dr. Fred S. Wouters, University of Göttingen

Prof. Dr. Martin Lohse, University of Würzburg

Prof. Dr. Stephan J. Sigrist, University of Würzburg

Dr. Stefan Eimer, European Neuroscience Institute-Göttingen