Science

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GEM Members: if you want to show on this page, and in a didactic way, your most recent and significant results, you can submit a text (French & English) and an image to the GEM secretariat: gem@univ-lyon1.fr. It will be published after consultation of the Scientific Committee.

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Assembly of multidrug efflux RND tripartite systems involved in antibiotics resistance

 

The team of Olivier Lambert, in collaboration with two other teams (Dr I. Broutin and Dr M. Picard from the University Paris Descartes and Pr K. Pos from the University of Frankfurt), managed for the first time to assemble MFP-RND-OMF tripartite efflux multidrug systems, involved in the antibiotic resistance phenomena, from native protein components in a membrane environment using lipid nanodiscs (Nanodiscs). Structural analysis by single particle electron microscopy has solved the structure of the tripartite system from Pseudomonas aeruginosa (MexA-MexB-OprM) and from Escherichia coli (AcrA-AcrB-TolC). This work has shown the importance of the periplasmic MFP adaptor protein as part of the exit duct between the inner RND and outer OMF membrane components which do not interact directly. Eventually, this protocol of tripartite system assembly could be used for assessing the efficacy of inhibitory compounds.

Broutin & Lambert Nature

Reference: Laetitia Daury, FrançoisOrange, Jean-Christophe Taveau,  Alice Verchère, Laura Monlezun, Céline Gounou, Ravi K Marredy, Martin Picard,  Isabelle Broutin,  Klass M Pos & Olivier Lambert.Tripartite assembly of RND multidrug efflux pumps. Nature Communication 2016 Feb 12;7:10731.

Contact: Olivier Lambert, CBMN, UMR5248 CNRS University of Bordeaux, Pessac. 

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Endocytosis decrypted

 

A recent study by Henri-François Renard, Ludger Johannes and colleagues has provided new insights into the mechanisms that operate in the cellular process of clathrin-independent endocytosis. Amongst other cargoes, this pathway is used by the bacterial Shiga toxin. After its binding to the cell surface, this toxin induces tubular plasma membrane invaginations as a first step of its uptake into cells. The scission of these tubules, which is essential for toxin internalization, requires their scaffolding by a cellular protein, endophilin A2, and the action of cellular engines that pull on this invagination. This study reveals a new membrane scission mechanism which acts in concert with those involving actin and dynamin.

Reference: Henri-François Renard, Mijo Simunovic, Joël Lemière, Emmanuel Boucrot, Maria Daniela Garcia-Castillo, Senthil Arumugam, Valérie Chambon, Christophe Lamaze, Christian Wunder, Anne K. Kenworthy, Anne A. Schmidt, Harvey T. McMahon, Cécile Sykes, Patricia Bassereau & Ludger Johannes. Endophilin-A2 functions in membrane scission in clathrin-independent endocytosis. Nature 517, 493-+ (2015), DOI: 10.1038/nature14064

Contact: Ludger Johannes, Institut Curie, U1143 INSERM/UMR3666 CNRS,  Paris. 

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