Système de sécrétion de type IV et protéines à domaines ankyrines dans les interactions Wolbachia-arthropodes

Abstract : Wolbachia are intracellular Gram-negative bacteria that are reproductive manipulators of many arthropods. In the isopod Armadillidium vulgare, the Wolbachia wVulC strain induces male feminization. Here, we characterized two vir operons which are expressed in all host tissues and which encode a type IV secretion system (T4SS) used to translocate bacterial effectors into host cytoplasm. Gene organization and sequence comparison in 37 Wolbachia strains highlighted the high conservation of both vir operons and their importance for the biology of the bacteria. We also identified in the on-going assembly of the wVulC genome, 66 ankyrin domain-encoding genes. Ankyrin motifs are known to mediate protein-protein interactions in eukaryotic organisms and thus are suggested to mediate in Wolbachia the interaction with host molecules. We showed that one of the three copies of the wVulC pk2 gene is only expressed in feminizing strains but not in the three strains inducing cytoplasmic incompatibility in terrestrial isopods. The associated Pk2 protein could be involved in male feminization. We thus tested the interaction between three T4SS proteins and five ankyrins (including Pk2) via the yeast two-hybrid and CRAfT (Cre-recombinase Reporter Assay for Translocation) methods. None of the five ankyrin proteins were revealed to be secreted by the wVulC strain. Nevertheless, this promising approach may enable us to identify Wolbachia effectors.
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S. Pichon. Système de sécrétion de type IV et protéines à domaines ankyrines dans les interactions Wolbachia-arthropodes. Ecologie, Environnement. Université de Poitiers, 2009. Français. ⟨tel-00551985⟩

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