6RWK

MxiD N0 N1 and MxiG C-terminal domains of the Shigella type 3 secretion system

Summary for 6RWK

• Entry DOI: 10.2210/pdb6rwk/pdb
• Related: 6RWX 6RWY
• EMDB information: 10040 10045 10046
• Descriptor: Outer membrane protein MxiD, Protein MxiG (2 entities in total)
• Functional Keywords: type 3 secretion system, shigella, secretin, beta-sheet augmentation, protein transport
• Biological source: Shigella flexneri; More
• Total number of polymer chains: 32
• Total formula weight: 1700548.13

Authors

Kamprad, A.,Lunelli, M. (deposition date: 2019-06-05, release date: 2020-02-12, Last modification date: 2024-05-22)

Primary citation

Lunelli, M.,Kamprad, A.,Burger, J.,Mielke, T.,Spahn, C.M.T.,Kolbe, M.
Cryo-EM structure of the Shigella type III needle complex.
Plos Pathog., 16:e1008263-e1008263, 2020

PubMed Abstract: 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 β-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.

PubMed: 32092125
DOI: 10.1371/journal.ppat.1008263

Experimental method

ELECTRON MICROSCOPY (3.86 Å)