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Institut de Biologie StructuraleGrenoble / France

Mechanism for assembling pores on the bacterial surface : a strategy for secreting toxins

Bacteria have developed different secretion systems that allow them to secrete toxins to the outside of the cell. These machines are important for infection, colonization and microbial communication processes. An important element of many of these machines is secretin, a membrane protein that forms a pore on the bacterial surface allowing toxins to escape. Using cryo electron microscopy, crystallography, and microbial genetics techniques, the MEM and PATBAC groups of IBS, in collaboration with the University of Saskatchewan in Canada, solved the structure (at approximately 3.5 Å resolution) of two secretins from the emerging pathogens Vibrio vulnificus and Aeromonas hydrophila and characterized the mechanism for their assembly on the bacterial membrane. This work has shown that the assembly of some secretins requires the help of membrane lipo-proteins called "pilotins", while others are assembled independently. Since the secretin-pilotin interface is essential for the virulence of many pathogens, it could be an original target for the development of new inhibitors of infections caused by bacteria.

Structure and assembly of pilotin-dependent and -independent secretins of the Type II secretion system. Howard SP, Estrozi L, Contreras-Martel C, Bertrand Q, Job V, Martins A, Schoehn G, Dessen A. PLoS Pathogens ; 15(5):e1007731