Identification of the essential Brucella melitensis Omp2b porin as a modulator of cell death using a genome‐wide functional yeast‐based screening

Laloux, Géraldine [FUNDP]

(eng) This thesis is in line with the global context of the identification and characterization of bacterial effectors responsible for the hijacking of the host cell, and particularly with the identification of anti-apoptotic effectors of Brucella spp. The introduction of this work is divided in three chapters, corresponding to the three "themes" that have been approached during this thesis: The first chapter of the introduction is centered on the modulation of one cellular process, apoptosis, by bacteria. The underlying mechanisms leading to apoptosis and the involvement of this particular cell death during infection will be approached. Our points of interest considering the modulation of apoptosis by our model pathogenic bacteria, Brucella spp., will be described. The second chapter of the introduction is related to yeast-based strategies aiming at the identification of bacterial effectors, including the strategy that we used to highlight new bacterial modulators of cell death. This chapter is thus justified by the aim of this thesis, which was to apply an original strategy to identify candidate anti-apoptotic proteins of B. melitensis, using the yeast S. cerevisiae as a tool for a genome-wide screening method. This screen shed light on two candidate proteins, and the one on which we mainly focused our attention is a porin. Thus, for reasons linked to the understanding of the results that will follow, the third chapter of our introduction is an annex dedicated to a general overview of porins, their implication regarding host-pathogen interactions and a summary of data that have already been published about Brucella porins. The results obtained in the frame of this thesis are mainly presented in a format that is convenient for their submission as a manuscript for a scientific journal. This manuscript, slightly modified in order to fulfill the journal requirements, is currently under submission in FEBS Letters. An additional part, presented in the results section after the paper manuscript, contains a description of the screening strategy, more detailed and illustrated than the corresponding part included in the paper manuscript, as well as supplementary information and data. The last section of this thesis is a discussion of the results, including suggestions for future work.