Activities of enteropathogenic/enterohemorrhagic E. coli effector proteins

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Diarrhoeal disease is a major human health problem which can be held accountable for roughly 2 million deaths each year. Among the bacterial agents causing diarrhoeal disease are the enteropathogenic E. coli (EPEC) and the closely related enterohemorrhagic E. coli (EHEC). Both, EPEC and EHEC cause disease by intimately attaching to host intestinal cells, and inducing the degeneration of absorptive microvilli. Although both are extracellular pathogen, they inject a plethora of effector proteins into the host cell, which affect many cellular functions. One extensively studied example of such a subversion of host cell mechanisms is the reorganisation of the cellular actin cytoskeleton to form actin pedestals under the attaching bacteria, a process that is known to be crucial for efficient colonisation. While the mode of action of some E. coli effector proteins has been explained, there are still a number of proteins delivered to the host cell by EPEC/EHEC whose function is unknown to date. The aim of the proposed research project is to elucidate the functions of selected EHEC/EPEC effector proteins in the eukaryotic cell and also to further throw light on the different mechanisms used by these bacteria to manipulate and infect the host cell. As many bacterial effector proteins have redundant and/or cooperative functions, they have little or no known phenotype when mutated in EPEC/EHEC. Thus, the genetic approach will be complemented and backed up by in vitro studies. These will entail the cloning and purification of selected bacterial effector proteins, which will allow for the identification of novel eukaryotic targets. The protein-protein interaction identified in vitro will then be validated using cell culture based models.