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Architecture of the major component of the type III secretion system export apparatus

DOI: 10.1038/nsmb.2452 DOI Help
PMID: 23222644 PMID Help

Authors: Patrizia Abrusci (University of Oxford) , Marta Vergara-irigaray (Oxford University; Imperial College London) , Steven Johnson (Oxford University) , Morgan D. Beeby (California Institute of Technology) , David R. Hendrixson (UT Southwestern Medical Center) , Pietro Roversi (Oxford University) , Miriam E. Friede (Oxford University) , Janet E. Deane (Oxford University) , Grant J. Jensen (California Institute of Technology) , Christoph M. Tang (Oxford University) , Susan Lea (Oxford University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Structural & Molecular Biology , VOL 20 (1) , PAGES 99 - 104

State: Published (Approved)
Published: December 2012
Diamond Proposal Number(s): 7495

Open Access Open Access

Abstract: Type III secretion systems (T3SSs) are bacterial membrane–embedded nanomachines designed to export specifically targeted proteins from the bacterial cytoplasm. Secretion through T3SS is governed by a subset of inner membrane proteins termed the 'export apparatus'. We show that a key member of the Shigella flexneri export apparatus, MxiA, assembles into a ring essential for secretion in vivo. The ring-forming interfaces are well-conserved in both nonflagellar and flagellar homologs, implying that the ring is an evolutionarily conserved feature in these systems. Electron cryo-tomography revealed a T3SS-associated cytoplasmic torus of size and shape corresponding to those of the MxiA ring aligned to the secretion channel located between the secretion pore and the ATPase complex. This defines the molecular architecture of the dominant component of the export apparatus and allows us to propose a model for the molecular mechanisms controlling secretion.

Journal Keywords: Bacterial; Bacterial; Biological; Cell; Models; Molecular; Protein; Secondary; Shigella flexneri

Subject Areas: Medicine

Instruments: I03-Macromolecular Crystallography

Other Facilities: ESRF

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