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Export apparatus core and inner rod of the Shigella type 3 secretion system
Structural highlights
Function[SPAQ_SHIFL] Required for surface presentation of invasion plasmid antigens. Could play a role in preserving the translocation competence of the Ipa antigens. Required for invasion and for secretion of the three Ipa proteins. [SPAP_SHIFL] Required for surface presentation of invasion plasmid antigens. Could play a role in preserving the translocation competence of the ipa antigens. Required for invasion and for secretion of the three Ipa proteins. [MXIH_SHIFL] Necessary for the secretion of IPA invasins. [SPAR_SHIFL] Required for surface presentation of invasion plasmid antigens. Could play a role in preserving the translocation competence of the ipa antigens. Required for invasion and for secretion of the three ipa proteins. Publication Abstract from PubMedThe 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 beta-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. Cryo-EM structure of the Shigella type III needle complex.,Lunelli M, Kamprad A, Burger J, Mielke T, Spahn CMT, Kolbe M PLoS Pathog. 2020 Feb 24;16(2):e1008263. doi: 10.1371/journal.ppat.1008263. PMID:32092125[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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