A conserved structural motif mediates formation of the periplasmic rings in the type III secretion system

TitleA conserved structural motif mediates formation of the periplasmic rings in the type III secretion system
Publication TypeJournal Article
Year of Publication2009
AuthorsSpreter, T., Yip C. K., Sanowar S., André I., Kimbrough T. G., Vuckovic M., Pfuetzner R. A., Deng W., Yu A. C., Finlay B. B., Baker D., Miller S. I., & Strynadka N. C. J.
JournalNature structural & molecular biology
Volume16
Issue5
Pagination468-76
Date Published2009 May
ISSN1545-9985
KeywordsAmino Acid Motifs, Bacterial Proteins, Collaborative Publication, Conserved Sequence, Crystallography, X-Ray, Membrane Transport Proteins, Models, Molecular, Periplasm, Protein Structure, Secondary, Protein Structure, Tertiary, Protein Transport, Salmonella typhimurium, Secretin, Structure-Activity Relationship, Virulence Factors
Abstract

The type III secretion system (T3SS) is a macromolecular 'injectisome' that allows bacterial pathogens to transport virulence proteins into the eukaryotic host cell. This macromolecular complex is composed of connected ring-like structures that span both bacterial membranes. The crystal structures of the periplasmic domain of the outer membrane secretin EscC and the inner membrane protein PrgH reveal the conservation of a modular fold among the three proteins that form the outer membrane and inner membrane rings of the T3SS. This leads to the hypothesis that this conserved fold provides a common ring-building motif that allows for the assembly of the variably sized outer membrane and inner membrane rings characteristic of the T3SS. Using an integrated structural and experimental approach, we generated ring models for the periplasmic domain of EscC and placed them in the context of the assembled T3SS, providing evidence for direct interaction between the outer membrane and inner membrane ring components and an unprecedented span of the outer membrane secretin.

Alternate JournalNat. Struct. Mol. Biol.
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