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Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation
Published on: January 4, 2017
Structure of a type IV secretion system core complex.
Rémi Fronzes1, Eva Schäfer, Luchun Wang
1Institute of Structural and Molecular Biology, School of Crystallography, Birkbeck College, Malet Street, London, WC1E 7HX, UK.
Science (New York, N.Y.)
|January 10, 2009
Summary
Type IV secretion systems (T4SSs) are crucial for bacterial virulence and antibiotic resistance spread. This study reveals the high-resolution cryo-electron microscopy structure of the T4SS core complex, detailing its unique double-walled channel architecture.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Biology
Background:
- Type IV secretion systems (T4SSs) are essential virulence factors in Gram-negative pathogens.
- T4SSs facilitate effector protein delivery into host cells and the spread of antibiotic resistance genes.
- Understanding T4SS structure is key to developing novel antimicrobial strategies.
Purpose of the Study:
- To determine the high-resolution structure of the core complex of a Type IV secretion system (T4SS).
- To elucidate the architectural and compositional features of the T4SS core complex.
- To compare the T4SS core complex structure with other known secretion systems.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was employed to determine the structure.
- The resolution achieved was 15 angstroms.
- The core complex was analyzed for its protein composition and overall architecture.
Main Results:
- The T4SS core complex structure was resolved at 15 angstrom resolution.
- The complex comprises three proteins, each in 14 copies, forming a ~1.1-megadalton double membrane-spanning channel.
- The channel is double-walled, open on the cytoplasmic side, and constricted extracellularly, differing from other secretion systems.
Conclusions:
- The determined structure provides unprecedented insight into T4SS machinery.
- The unique architecture suggests specific mechanisms for substrate translocation and host-pathogen interactions.
- This structural information can guide the development of new therapeutics targeting bacterial virulence.
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