Elisabeth Fischer-Friedrich
Minerva Postdoctoral Fellow with
Nir Gov and Samuel Safran
Weizmann Institute of Science, Rehovot, Israel




Research Interests

The object of my research is to understand biological systems from first principles using tools from mathematics, physics and biology. Trained as a theoretical physicist, I focus on the derivation of adequate theoretical descriptions and filtering of the essential features of a biological system to understand its behaviour. I appreciate close proximity to experimental work to really get an idea of the character of the biological system and the accessibility of experimental aims.


Current projects

Cytoskeletal FtsZ structures in bacteria (with Nir Gov)

FtsZ is a cytoskeletal protein which is present in most bacteria and archae. It scaffolds the contractile ring, the so-called Z-ring, which constricts the bacterium during cell division. In the presence of GTP, FtsZ polymerizes into single-stranded protofilaments. Experiments have shown that the Z-ring consists of many FtsZ polymers, tethered to the inner cytoplasmic membrane. In addition to the Z-ring, helical structures of FtsZ have been observed beneath the inner bacterial membrane, partly in coexistence with the Z-ring. Both rings and helices are dynamic and can transform one into another. How FtsZ structures are formed in the cell is at present not understood. We plan to study which physical mechanisms can drive the formation of FtsZ rings and helices and establish a theoretical analysis of the system.

Figure 1: a) The Z-ring in two Escherichia coli cells of the strain EC448. The left image shows the cells in a phase contrast micrograph. The image on the right shows the fluorescently labeled protein FtsZ constituting the Z-ring which forms prior to cell division.






Pattern formation by the Min system of Escherichia coli (Phd thesis with Karsten Kruse)

During my PhD-thesis, I have studied the Min-system of Escherichia coli. The Min system consists of the proteins MinC, MinD and MinE which are expressed in the bacterium. These proteins have been found to form spatiotemporal patterns in the cell by oscillating from one cell pole to the other (see Figure 2). This behaviour helps the bacterium to localize its septum during cell division.


Figure 2: Oscillation of MinD (a and b) and MinE (c) in Escherichia coli cells. a) Time series of a cell with fluorescently labeled MinD. The leftmost image shows the cell in a DIC-micrograph. The remaining images show fluorescently labeled GFP-MinD in the cell for ascending times. MinD maxima locate to one cell pole and switch to the opposite pole after a characteristic residence time.

b) Kymograph of fluorescently labeled MinD. The leftmost image shows the cell at time= 0s and indicates how the kymograph was produced. The fluorescence was recorded along the red line and averaged over the line width.

c) Kymograph of fluorescently labeled MinE in an E. coli cell. The scale bars show 1min.


We have established a coarse-grained description of the Min oscillations which is able to reproduce essential features of the Min system on the basis of self-organization of the Min proteins. To test the hypothesis that the Min patterns form by self-organization further we wanted to study the Min system (MinD, MinE and ATP) in an isolated in vitro environment on a flat supported lipid bilayer. The associated experiments were performed by our collaborator Martin Loose in the Lab of Prof. Schwille. The results were that, indeed, Min proteins are able to form beautiful self-orgainizing patterns in vitro.

Figure 3: Min waves in vitro and in silico.

a) Experimental data: Min waves form on a supported lipid bilayer. Shown is the fluorescence of labeled MinE.

b) Model of the Min system: our coarse-grained model generates similar patterns on a flat surface. Shown is the concentration of MinE, in accordance to the experimental picture.



List of publications:


How to contact me

office: Perlman building, room 5-19b

telephone: +972 8 934 3363

email: elisabeth(dot)fischerfriedrich(at)gmail(dot)com