%0 Journal Article
%T Cryo-EM structure of the Shigella type III needle complex
%A Antje Kamprad
%A Christian M. T. Spahn
%A J£¿rg B¨¹rger
%A Michael Kolbe
%A Michele Lunelli
%A Thorsten Mielke
%J -
%D 2020
%R 10.1371/journal.ppat.1008263
%X The Type III Secretion Systems (T3SS) needle complex is a conserved syringe-shaped protein translocation nanomachine with a mass of about 3.5 MDa essential for the survival and virulence of many Gram-negative bacterial pathogens. This system is composed of a membrane-embedded basal body and an extracellular needle that deliver effector proteins into host cells. High-resolution structures of the T3SS from different organisms and infection stages are needed to understand the underlying molecular mechanisms of effector translocation. Here, we present the cryo-electron microscopy structure of the isolated Shigella T3SS needle complex. The inner membrane (IM) region of the basal body adopts 24-fold rotational symmetry and forms a channel system that connects the bacterial periplasm with the export apparatus cage. The secretin oligomer adopts a heterogeneous architecture with 16- and 15-fold cyclic symmetry in the periplasmic N-terminal connector and C-terminal outer membrane ring, respectively. Two out of three IM subunits bind the secretin connector via a ¦Â-sheet augmentation. The cryo-EM map also reveals the helical architecture of the export apparatus core, the inner rod, the needle and their intervening interfaces
%K Shigella
%K Salmonella
%K Secretin
%K Hydrogen bonding
%K Secretion systems
%K Electrostatics
%K Protein structure
%K Electron cryo-microscopy
%U https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1008263