Structural and functional studies on the N-terminal domain of the Shigella type 
III secretion protein MxiG

McDowell, Melanie A.; Johnson, Steven; Deane, Janet E.; Cheung, Martin; Roehrich, A. Dorothea; Blocker, Ariel J.; McDonnell, James M.; Lea, Susan M.

doi:10.1074/jbc.M111.243865

Item

ITEM ACTIONSEXPORT

Add to Basket

Local TagsRelease HistoryDetailsSummary

Released

Journal Article

Structural and functional studies on the N-terminal domain of the Shigella type III secretion protein MxiG

MPS-Authors

There are no MPG-Authors in the publication available

External Resource

No external resources are shared

Fulltext (restricted access)

There are currently no full texts shared for your IP range.

Fulltext (public)

There are no public fulltexts stored in PuRe

Supplementary Material (public)

There is no public supplementary material available

Citation

McDowell, M. A., Johnson, S., Deane, J. E., Cheung, M., Roehrich, A. D., Blocker, A. J., et al. (2011). Structural and functional studies on the N-terminal domain of the Shigella type III secretion protein MxiG. The Journal of Biological Chemistry, 286(35), 30606-30614. doi:10.1074/jbc.M111.243865.

Cite as: https://hdl.handle.net/21.11116/0000-0009-696F-6

Abstract

MxiG is a single-pass membrane protein that oligomerizes within the inner membrane ring of the Shigella flexneri type III secretion system (T3SS). The MxiG N-terminal domain (MxiG-N) is the predominant cytoplasmic structure; however, its role in T3SS assembly and secretion is largely uncharacterized. We have determined the solution structure of MxiG-N residues 6-112 (MxiG-N(6-112)), representing the first published structure of this T3SS domain. The structure shows strong structural homology to forkhead-associated (FHA) domains. Canonically, these cell-signaling modules bind phosphothreonine (Thr(P)) via highly conserved residues. However, the putative phosphate-binding pocket of MxiG-N(6-112) does not align with other FHA domain structures or interact with Thr(P). Furthermore, mutagenesis of potential phosphate-binding residues has no effect on S. flexneri T3SS assembly and function. Therefore, MxiG-N has a novel function for an FHA domain. Positioning of MxiG-N(6-112) within the EM density of the S. flexneri needle complex gives insight into the ambiguous stoichiometry of the T3SS, supporting models with 24 MxiG subunits in the inner membrane ring.