Institute of Microbiology

Student: Analysis of effector proteins injected via the Salmonella Type III secretion system

Group: Hardt
Position: Semesterarbeit / Diplomarbeit
Contact: Prof. Dr. Wolf Dietrich Hardt
Institute of Microbiology
Wolfgang-Pauli-Str. 10
HCI G 417
ETH Zürich
CH-8093 Zürich

Phone: +41(0)44 632 5143
Description: Salmonella typhimurium is one of the leading causes of bacterial food poisoning. The project analyzes the pathogenetic mechanisms of Salmonella infections. A protein injection organelle (called typeIII secretion system) is of key importance in the induction of diarrhea because it allows the bacterium to inject protein toxins directly into cells of the host’s intestine. The candidate is going to use cell culture infection experiments to analyze at a molecular level how the injected Salmonella toxins manipulate host cell signaling pathways.

So we have found that one of the protein toxins (SopE) injected into host cells acts as a specific G-nucleotide exchange factor (Hardt et al., 1998). SopE specifically activates Cdc42- and Rac1-signalling inside the host cell (all references). However, besides SopE, S. Typhimurium injects at least 12 additional protein toxins into host cells which contribute to the manipulation of host cellular signaling (i.e. actin polymerization, intracellular Ca2+- and phosphatidylinositol-levels, chloride secretion) pathways in unknown ways.

The project is going to analyze the function of two Salmonella toxins, which have not been characterized so far. It will involve recombinant DNA techniques, tissue culture, immunofluorescence microscopy (including live cell imaging), transient transfection experiments, cell biology and protein purification.


  • Buchwald, G., A. Friebel, J. E. Galan, W. D. Hardt, A. Wittinghofer, and K. Scheffzek. 2002. Structural basis for the reversible activation of a Rho protein by the bacterial toxin SopE. EMBO J 21:3286-95.
  • Friebel, A., H. Ilchmann, M. Aelpfelbacher, K. Ehrbar, W. Machleidt, and W. D. Hardt. 2001. SopE and SopE2 from Salmonella typhimurium activate different sets of RhoGTPases of the host cell. Journal of Biological Chemistry 276:34035-40.
  • Hardt, W. D., L. M. Chen, K. E. Schuebel, X. R. Bustelo, and J. E. Galan. 1998. S. typhimurium encodes an activator of Rho GTPases that induces membrane ruffling and nuclear responses in host cells. Cell 93:815-26.
  • Rudolph, M. G., C. Weise, S. Mirold, B. Hillenbrand, B. Bader, A. Wittinghofer, and W. D. Hardt. 1999. Biochemical analysis of SopE from Salmonella typhimurium, a highly efficient guanosine nucleotide exchange factor for RhoGTPases. J Biol Chem 274:30501-9.
  • Schlumberger, M. C., A. Friebel, G. Buchwald, K. Scheffzek, A. Wittinghofer, and W. D. Hardt. 2003. Amino acids of the bacterial toxin SopE involved in G-nucleotide exchange on Cdc42. J Biol Chem. 278:27149-59.
Time frame:
as agreed

Wichtiger Hinweis:
Diese Website wird in älteren Versionen von Netscape ohne graphische Elemente dargestellt. Die Funktionalität der Website ist aber trotzdem gewährleistet. Wenn Sie diese Website regelmässig benutzen, empfehlen wir Ihnen, auf Ihrem Computer einen aktuellen Browser zu installieren. Weitere Informationen finden Sie auf
folgender Seite.

Important Note:
The content in this site is accessible to any browser or Internet device, however, some graphics will display correctly only in the newer versions of Netscape. To get the most out of our site we suggest you upgrade to a newer browser.
More information

© 2015 Microbiology ETH Zürich | Imprint | Disclaimer | 24 July 2013