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Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation
Published on: January 4, 2017
Atomic model of the type III secretion system needle.
Antoine Loquet1, Nikolaos G Sgourakis, Rashmi Gupta
1Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Nature
|June 16, 2012
Summary
Pathogenic bacteria use type III secretion systems (T3SS) to infect hosts. Researchers determined the atomic structure of the Salmonella typhimurium T3SS needle, revealing a novel helical assembly with surface-exposed N-termini.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Type III secretion systems (T3SS) are crucial virulence factors for many pathogenic bacteria.
- The T3SS needle facilitates effector protein injection into host cells, but its atomic structure remains elusive due to technical challenges.
- Previous low-resolution models lacked crucial details of subunit interfaces.
Purpose of the Study:
- To determine the complete atomic structure of the Salmonella typhimurium T3SS needle.
- To elucidate the supramolecular interfaces and assembly of the T3SS needle subunits.
Main Methods:
- Combined recombinant protein production, solid-state NMR, electron microscopy, and Rosetta computational modeling.
- Utilized a hybrid approach to overcome limitations of traditional structural biology techniques.
Main Results:
- Revealed the T3SS needle is a right-handed helical assembly of 80-residue subunits (approx. 11 subunits per two turns).
- The N-terminal domain is positioned on the needle surface, contrary to previous models.
- The conserved C-terminus is oriented towards the needle lumen.
Conclusions:
- The study provides the first atomic-level structural model of the T3SS needle.
- This detailed structure offers insights into T3SS assembly and function.
- The findings advance our understanding of bacterial pathogenesis and potential therapeutic targets.
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