Schmutz, Christoph. Host protein phosphorylation during "Shigella flexneri" infection : a phosphoproteomic based systems biology approach. 2015, PhD Thesis, University of Basel, Faculty of Science.
Official URL: http://edoc.unibas.ch/diss/DissB_11253
cytoskeleton, signal transduction, cell cycle, and transcription regulation. The temporal phosphorylation patterns were addressed by fuzzy c-means clustering, revealing six temporally distinct phosphorylation profiles as well as kinases potentially responsible for these phosphorylations. In particular, we found a cluster of ataxia telangiectasia mutated (ATM) substrates, related to genotoxic stress, that became phosphorylated at a late
stage of infection. We identified mTOR as the most overrepresented signaling pathway and could demonstrate that both, mTORC1 and mTORC2, become activated during S. flexneri infection. To identify phosphoproteins commonly regulated during bacterial infection, we compared our dataset to a published phosphoproteome of cells infected with Salmonella typhimurium. This analysis revealed a large subset of co-regulated phosphoproteins, indicating that both pathogens interfere with similar cellular signaling cascades. Furthermore, we addressed the impact of the S. flexneri effector protein OspF on the host phosphorylation network. OspF is known to inactivate the MAPKs p38 and ERK. The phosphorylation of several hundred proteins was affected in an OspF-dependent manner, demonstrating the massive impact a single bacterial effector can have on the host signaling network.
In a second project we addressed the activation mechanism of AKT and mTOR during S. flexneri infection by studying the effector IpgD. IpgD is a phosphoinositide 4-phosphatase
generating PI5P from PI(4,5)P2 leading to activation of AKT. We could demonstrate that the effector protein IpgD is sufficient to induce mTOR activation by the use of a protein
delivery tool based on the TTSS of Yersinia enterocolitica. Interestingly, AKT activation was independent of canonical PI3K activity shortly after IpgD translocation, whereas at
later timepoints AKT activation was PI3K-dependent. These data suggest two distinct IpgD-dependent AKT activation mechanisms. Finally, we could show that the Inositol polyphosphate multikinase IPMK contributes to AKT phosphorylation during infection.
|Committee Members:||Dehio, Christoph|
|Faculties and Departments:||05 Faculty of Science > Departement Biozentrum > Infection Biology > Molecular Microbiology (Arrieumerlou)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||177 S.|
|Last Modified:||30 Jun 2016 10:57|
|Deposited On:||10 Jun 2015 13:03|
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