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11:33
Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
Published on: December 17, 2013
Structural characterization of the molecular platform for type III secretion system assembly
Calvin K Yip1, Tyler G Kimbrough, Heather B Felise
1Department of Biochemistry and Molecular Biology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, British Columbia, Canada V6T 1Z3.
Nature
|June 3, 2005
Summary
Type III secretion systems (TTSSs) are crucial for pathogen virulence. This study reveals the 24-subunit ring structure of EscJ, a key component, providing a molecular platform for TTSS assembly.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Biology
Background:
- Type III secretion systems (TTSSs) are essential virulence factors in Gram-negative pathogens.
- They translocate bacterial effector proteins into host cells.
- Understanding TTSS structure is key to developing antivirulence strategies.
Purpose of the Study:
- To determine the structural characteristics of EscJ, a TTSS component.
- To elucidate the oligomerization and assembly mechanism of TTSSs.
- To propose a model for the function of the YscJ/PrgK protein family.
Main Methods:
- X-ray crystallography (1.8-Å resolution) of EscJ.
- Crystal packing analysis and molecular modeling.
- Electron microscopy, labeling, and mass spectrometry of PrgK.
Main Results:
- The crystal structure of EscJ was determined.
- Molecular modeling suggests EscJ forms a 24-subunit ring structure.
- Experimental data support the ring model's stoichiometry, membrane association, and accessibility.
Conclusions:
- The YscJ/PrgK protein family forms a ring-like molecular platform.
- This platform is essential for the assembly of Type III secretion systems.
- The findings provide insights into TTSS biogenesis and potential therapeutic targets.
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