2 research outputs found
Pseudomonas fluorescens MFE01 delivers a putative type VI secretion amidase that confers biocontrol against the softârot pathogen Pectobacterium atrosepticum
International audienceThe type VI secretion system (T6SS) is a contractile nanomachine widespread in Gramânegative bacteria. The T6SS injects effectors into target cells including eukaryotic hosts and competitor microbial cells and thus participates in pathogenesis and intermicrobial competition. Pseudomonas fluorescens MFE01 possesses a single T6SS gene cluster that confers biocontrol properties by protecting potato tubers against the phytopathogen Pectobacterium atrosepticum (Pca). Here, we demonstrate that a functional T6SS is essential to protect potato tuber by reducing the pectobacteria population. Fluorescence microscopy experiments showed that MFE01 displays an aggressive behaviour with an offensive T6SS characterized by continuous and intense T6SS firing activity. Interestingly, we observed that T6SS firing is correlated with rounding of Pectobacterium cells, suggesting delivery of a potent cell wall targeting effector. Mutagenesis coupled with functional assays then revealed that a putative T6SS secreted amidase, Tae3 Pf , is mainly responsible for MFE01 toxicity towards Pca. Further studies finally demonstrated that Tae3 Pf is toxic when produced in the periplasm, and that its toxicity is counteracted by the Tai3 Pf inner membrane immunity protein
Fleuves, estuaires et cours d'eau : représentations et pratiques
Ce numĂ©ro thĂ©matique de VertigO invite Ă voyager dans le temps et lâespace, et Ă nourrir la connaissance hydrologique des cultures de lâeau dans lesquelles elle sâinscrit. Lâeau est une source infinie de lâimagination scientifique, et ce numĂ©ro en rĂ©vĂšle certaines dynamiques : production dâobjets (zones humides, espĂšces invasives, hydrosystĂ©mie), protocoles et programmes de recherche (de la zone atelier aux politiques ministĂ©rielles), quĂȘte Ă©ternelle de la source explicative (des eaux souterraines Ă lâanthroposystĂšme). La pensĂ©e hydrologique, dans sa forme scientifique, est au fond relativement rĂ©cente, et relie les hommes, via des controverses scientifiques ou Ă travers des syndicats de gestion, autant quâelle distingue ceux qui en maĂźtrisent lâusage technique et les enjeux, de ceux qui entretiennent dâautres rapports aux milieux. Quels sont ces rapports ? Quels sont ces milieux