4TT9

Structure of the C-terminal SpoA domain of Shigella flexneri Spa33

Summary for 4TT9

• Entry DOI: 10.2210/pdb4tt9/pdb
• Descriptor: Surface presentation of antigens protein SpaO, 1,2-ETHANEDIOL (3 entities in total)
• Functional Keywords: t3ss, c-ring, spoa, flin, immune system, protein transport
• Biological source: Shigella flexneri
• Total number of polymer chains: 4
• Total formula weight: 39785.01

Authors

McDowell, M.A.,Johnson, S.,Lea, S.M. (deposition date: 2014-06-20, release date: 2015-06-24, Last modification date: 2023-12-20)

Primary citation

McDowell, M.A.,Marcoux, J.,McVicker, G.,Johnson, S.,Fong, Y.H.,Stevens, R.,Bowman, L.A.,Degiacomi, M.T.,Yan, J.,Wise, A.,Friede, M.E.,Benesch, J.L.,Deane, J.E.,Tang, C.M.,Robinson, C.V.,Lea, S.M.
Characterisation of Shigella Spa33 and Thermotoga FliM/N reveals a new model for C-ring assembly in T3SS.
Mol.Microbiol., 99:749-766, 2016

PubMed Abstract: Flagellar type III secretion systems (T3SS) contain an essential cytoplasmic-ring (C-ring) largely composed of two proteins FliM and FliN, whereas an analogous substructure for the closely related non-flagellar (NF) T3SS has not been observed in situ. We show that the spa33 gene encoding the putative NF-T3SS C-ring component in Shigella flexneri is alternatively translated to produce both full-length (Spa33-FL) and a short variant (Spa33-C), with both required for secretion. They associate in a 1:2 complex (Spa33-FL/C2) that further oligomerises into elongated arrays in vitro. The structure of Spa33-C2 and identification of an unexpected intramolecular pseudodimer in Spa33-FL reveal a molecular model for their higher order assembly within NF-T3SS. Spa33-FL and Spa33-C are identified as functional counterparts of a FliM-FliN fusion and free FliN respectively. Furthermore, we show that Thermotoga maritima FliM and FliN form a 1:3 complex structurally equivalent to Spa33-FL/C2 , allowing us to propose a unified model for C-ring assembly by NF-T3SS and flagellar-T3SS.

PubMed: 26538516
DOI: 10.1111/mmi.13267

Experimental method

X-RAY DIFFRACTION (2.3 Å)