Structural Bioinformatics and Protein Design
(Gerd Krause)

Open positions


Doktorand(in) / PhD student

The DFG Research Training Group (GRK 2318) Tight Junction-Train offers a
PhD position (E13 65 %) in Natural and Life Sciences, Project A2
at the Charité - Universitätsmedizin Berlin together with the
Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin


Topic:             Structure-based modification of Clostridium perfringens enterotoxin to target claudins
(PD Dr. Jörg Piontek, Dr. Gerd Krause)

Clostridium perfringens enterotoxin (CPE) causes one of the most common food borne illnesses. CPE binds to tight junction (TJ) proteins (e.g. claudin-3 and -4) and subsequently forms pores in the membrane leading to damage of epithelial cells. Due to its cytotoxicity, CPE is used for targeting tumor cells that overexpress specific claudin-subtypes. In contrast, the isolated C-terminal domain of CPE (cCPE) is non-toxic and contains the claudin binding domain. cCPE is used as a TJ modulator to increase paracellular drug delivery. Previously, we elucidated in structure-based studies the molecular mechanism of the CPE-claudin interaction and designed CPE- and cCPE-variants with shifted subtype-specificity to claudins (e.g. binding to claudin-1 or -5 to which CPE-, cCPE-wt does not bind). We started to use these variants to (i) improve paracellular drug delivery in tissue barrier models, (ii) inhibit Hepatitis C Virus infection that depends on claudins and (iii) inhibit growth of thyroid and lung tumors growth.    

Aim of this project is to expand structure-function studies to design and to test also new variants of cCPE and CPE that target further claudins. These proteins will be used as novel tissue-specific modular biologicals for (i) improved drug delivery by TJ modulation, (ii) molecular diagnosis or (iii) cytotoxic treatment of carcinomas.

Methods: Molecular modelling driven site-directed mutagenesis, expression and purification of recombinant proteins, protein-protein interaction assays, cell culture of differentiated epithelial and transformed carcinoma cells, immunocytochemistry and live cell confocal microscopy. Activity of cCPE- and CPE-variants will be tested by measurements of transepithelial resistance and paracellular solute permeability, imaging of cell lines, mouse and human tissue samples as well as cytotoxicity assays with cell lines and in vivo xenotransplant tumor models.

Requirements: Very good Master/Diploma degree in Biology, Biochemistry, Biotechnology or a related field of study, first experience in molecular cell biology and a strong interest in molecular / structural details of protein-protein interactions. We offer a strong, committed and enthusiastic scientific environment at the interface between basic and preclinical research.

Contact and more informations: joerg.piontek(at); gkrause(at)

Guideline for online application:


Project-related publications

1. Piontek A, Eichner M, Zwanziger D, Beier LS, Protze J, Walther W, Theurer S, Schmid KW, Führer-Sakel D, Piontek J, Krause G (2020) Targeting claudin-overexpressing thyroid and lung cancer by modified Clostridium perfringens enterotoxin.
Mol Oncol. 14(2):261-276. doi: 10.1002/1878-0261.12615.

2. Beier LS, Rossa J, Woodhouse S, Bergmann S, Kramer HB, Protze J, Eichner M, Piontek A, Vidal-Y-Sy S, Brandner JM, Krause G, Zitzmann N, Piontek J (2019)  Use of Modified Clostridium perfringens Enterotoxin Fragments for Claudin Targeting in Liver and Skin Cells. Int J Mol Sci. 20(19). pii: E4774. doi: 10.3390/ijms20194774.

3. Neuhaus W, Piontek A, Protze J, Eichner M, Mahringer A, Subileau EA, Lee IM, Schulzke JD, Krause G, Piontek J. (2018) Reversible opening of the blood-brain barrier by claudin-5-binding variants of Clostridium perfringens enterotoxin's claudin-binding domain. Biomaterials. 161:129-143. doi: 10.1016/j.biomaterials.2018.01.028.



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