Cryo-EM structure of a type IV secretion system.
Kévin Macé1, Abhinav K Vadakkepat2, Adam Redzej2
1Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK. k.mace@mail.cryst.bbk.ac.uk.
Nature
|June 22, 2022
Summary
Bacterial conjugation, a key process for spreading antibiotic resistance, is mediated by the type IV secretion system (T4SS). This study reveals the high-resolution structure of the T4SS, detailing its complex assembly and pilus formation mechanism.
Area of Science:
- Microbiology
- Structural Biology
- Molecular Biology
Background:
- Bacterial conjugation facilitates the spread of antibiotic resistance genes.
- The type IV secretion system (T4SS) mediates DNA transfer in Gram-negative bacteria.
- The T4SS is a large complex involving outer and inner membrane proteins and an extracellular pilus.
Purpose of the Study:
- To determine the high-resolution cryo-electron microscopy (cryo-EM) structure of the bacterial conjugation T4SS complex.
- To elucidate the protein-protein interaction network essential for T4SS assembly and function.
- To gain insights into the mechanism of pilus biogenesis and DNA transfer.
Main Methods:
- High-resolution cryo-electron microscopy (cryo-EM) was used to determine the structure of the T4SS complex.
- The structure of a 2.8 megadalton complex comprising 92 polypeptides was resolved.
- Co-evolution analysis of protein interfaces was employed to model the missing T4SS components.
Main Results:
- A high-resolution structure of the T4SS complex, a 2.8 megadalton assembly, was determined.
- The structure reveals an extensive protein-protein interaction network crucial for T4SS assembly.
- The study provides a structural basis for understanding pilus elaboration and bacterial DNA transfer.
Conclusions:
- The determined T4SS structure offers unprecedented detail on the molecular architecture of this essential bacterial conjugation machinery.
- Understanding the T4SS assembly and pilus formation mechanism can inform strategies to combat antibiotic resistance spread.
- This work provides a foundation for future structural and mechanistic studies of type IV secretion systems.
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