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A Visual Assay to Monitor T6SS-mediated Bacterial Competition
Published on: March 20, 2013
Structural insights into the Type II secretion nanomachine.
Lorraine S McLaughlin1, Rembrandt J F Haft, Katrina T Forest
1Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
Current Opinion in Structural Biology
|March 20, 2012
Summary
The Type II secretion system uses a nanomachine to transport proteins across bacterial outer membranes. New structural data reveals how its components assemble and function, clarifying protein transport mechanisms.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Gram-negative bacteria utilize the Type II secretion system (T2SS) to export proteins across their outer membrane.
- The T2SS is a complex nanomachine composed of multiple protein subunits.
Purpose of the Study:
- To elucidate the structural organization and assembly mechanism of the T2SS nanomachine.
- To understand the functional interplay between T2SS components during protein transport.
Main Methods:
- X-ray crystallography
- Cryo-electron microscopy (cryo-EM)
- Molecular modeling
- Biochemical assays
Main Results:
- High-resolution cryo-EM reconstruction of the secretin, a key outer membrane pore.
- Demonstration of secretin interactions with secreted substrates and a transmembrane clamp protein.
- Biochemical and structural insights into the role of pseudopilins in pseudopilus formation.
Conclusions:
- A comprehensive 3D model of the T2SS nanomachine has been synthesized.
- Secretin oligomerization is proposed to define assembly sites for the nanomachine.
- The findings provide a stepwise pathway for T2SS biogenesis and protein transport.
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