David RIBET PhD Microbiology, CR1 INSERM

Course and current status

Since 2017 : Research Associate (CR1 INSERM) in "Nutrition, Inflammation and gut-brain axis dysfunctions" Lab (Pr. Pierre DECHELOTTE), Rouen University, Rouen, France.

2011-2017 : Research Associate (CR1 INSERM) in Bacteria-Cell Interactions Lab (Pr. Pascale COSSART), Institut Pasteur, Paris, France.

2007-2011 : Post-Doctoral fellow in Bacteria-Cell Interactions Lab (Pr. Pascale COSSART), Institut Pasteur, Paris, France.

2009 : Training in Cellular Microbiology (Diplôme Universitaire), University of Lille, France.

2007 : Ph.D. in Microbiology / Virology, Paris Diderot University, France.

2003 : Master's degree in Microbiology / Virology, Paris Diderot University, France.

2002 : Agrégation de Sciences de la Vie et de la Terre.

2001 : Bachelor's degree in Biochemistry, Paris Diderot University, France.

1999-2003 : Training in Ecole Normale Supérieure de Cachan, France.

Scientific summary

Role of SUMOylation during infection by bacterial pathogens

   Alteration of host post-translational modifications (PTMs) is a strategy used by pathogens to reprogram the activity of key host factors during infection. My research focuses on SUMOylation, a PTM closely related to ubiquitin. I started this project because the role of SUMOylation during bacterial infection was unexplored so far, despite the reported role of this PTM in key cellular processes. My work unveiled examples of how SUMOylation can regulate bacterial infection.

   Using Listeria monocytogenes, the bacterium responsible for human listeriosis, as a model of pathogen, we reported for the first time how bacteria can interfere with host SUMOylation to promote infection. Indeed, we showed that Listeria secretes a toxin that inhibits the host SUMOylation machinery and favours bacterial replication. Further understanding of the consequences of bacteria-induced SUMO alterations requires the identification of proteins SUMOylated or deSUMOylated in response to infection, which was at that time experimentally very challenging. To circumvent this technological limitation, I led the development of an innovative method based on mass spectrometry, allowing both identification of SUMOylated proteins and proteome-wide analysis of SUMOylation changes induced by external stimuli. We successfully applied this method to Listeria and identified host transcription as a SUMO-regulated process altered by this bacterium.

   In an age of bacterial resistance to antibiotics, such studies are essential to identify new key host factors for infection that may constitute targets for therapeutics development. The method we developed further allows studying SUMO changes in response to any kind of external stimuli, such as environmental stress, drug or toxin exposure. This innovative technology will provide new insights in various SUMO-regulated processes of the cell and help decipher previously unindentified roles of SUMOylation in cell physiology and diseases.

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