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Bayer CropScience


Accueil > Équipes > Trafic et signalisation membranaires chez les bactéries > Mécanismes moléculaires d’adaptation à des stress abiotiques

Molecular mechanisms of adaptation to abiotic stresses

Bacteria have to adapt to continually changing environments, such as biotic or abiotic stresses. The objectives of the present axis are to decipher several molecular mechanisms crucial for these adaptations. The main projects will be (1) to understand the exchanges through membranes and the conditions of membrane perturbation, and (2) to investigate the signaling and adaptive processes bacteria use to face envelop stresses.

Bacteria from the genus Dickeya are necrotrophic phytopathogens inducing soft-rot disease in many crops species, such as potato or chicory. We have also shown previously that Dickeya dadantii is able to infect and kill certain insects such as the pea aphid, using a toxin cluster and regulatory responses that are inverted as compared to plant virulence pathways. Such interactions with some insect groups could also participate in vectoring bacteria from plant to plant. We aim to decipher the factors allowing the interaction of the bacteria with its host insect or plant by various techniques such as Tn-Seq, with a specific focus towards the role of Cyt-like toxins, up-to-now only known in the model entomopathogenic bacteria Bacillus thuringiensis. Links between enterobacterial phytopathogens and hemipteran plant piercing-sucking insects are also studied by phylogenetic and phylogenomic approaches. Surface interactions between microbial phytopathogens and insect cuticular structures are also investigated, on the aphid model, by interdisciplinary approaches (EPI-Cuticule : microbiology – functional genomics – material science).

The production of antimicrobial peptides is one of the first defense mechanisms used by eukaryotic hosts infected by bacteria. We have shown that the D. dadantii response to antimicrobial peptides is original, both considering the molecular mechanisms of action and the regulation of the genetic determinants. Since the use of antimicrobial peptides to fight phytopathogenic bacteria is an expanding approach, it is crucial to understand the mechanisms by which bacteria can resist to these molecules. We will continue to characterize these mechanisms in D. dadantii.

Antibacterial compounds targeting the envelope, such as antimicrobial peptides, activate the Envelope Stress Response (ESR) pathways. Growing evidences suggest that metals play a crucial role in the signaling processes leading to the activation of the adaptive response for the survival of bacteria in contact with antimicrobial compounds. We investigate the underlying signaling mechanisms with a focus on the ZraP-ZraSR two-component signaling pathway in Escherichia coli.

Development of biotechnological tools. Our deep knowledge of bacterial interaction with metals at the cell, molecular and genetic scales, enable us to develop tools for the bioremediation of metals. We also develop whole cell biosensors for the monitoring of pollutants in water.