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Gram-negative Bacterial Protein Secretion Systems

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Related Experiment Video

Updated: Jul 16, 2026

A Visual Assay to Monitor T6SS-mediated Bacterial Competition

A Visual Assay to Monitor T6SS-mediated Bacterial Competition

Published on: March 20, 2013

The type III secretion system needle tip complex mediates host cell sensing and translocon insertion.

Andreas K J Veenendaal¹, Julie L Hodgkinson, Lynn Schwarzer

¹Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.

Molecular Microbiology

|March 21, 2007

Summary

The Shigella type III secretion system (T3SS) needle tip complex, involving IpaB and IpaD, senses host cells. This interaction orchestrates protein secretion and pore formation for bacterial invasion.

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Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking

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Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation

Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation

Published on: January 4, 2017

Area of Science:

Microbiology
Molecular Biology
Bacterial Pathogenesis

Background:

Type III secretion systems (T3SSs) are critical for virulence in Gram-negative pathogens.
The Shigella T3SS needle mediates host cell contact, sensing, and secretion.
Understanding T3SS needle tip function is crucial for deciphering bacterial invasion mechanisms.

Purpose of the Study:

To investigate the composition and function of the Shigella T3SS needle tip complex.
To elucidate the molecular events involved in host cell sensing and pore formation by the T3SS.

Main Methods:

Biochemical analyses of wild-type and mutant Shigella T3SS needles.
Immunological studies to characterize needle tip components and interactions.

Main Results:

Identified tip complexes with varying compositions and functional states.
Demonstrated the critical role of IpaB and IpaD interaction at the needle tip for host cell sensing.
Showcased the orchestration of IpaC secretion and its assembly for translocation pore formation.

Conclusions:

The IpaB-IpaD interaction at the T3SS needle tip is essential for host cell sensing.
This interaction regulates the secretion and membrane insertion of the translocation pore complex (IpaB/IpaC).
The T3SS needle tip acts as a dynamic sensor and regulator of bacterial effector protein delivery.