Related Experiment Video
Updated: May 26, 2026
08:36
Quantifying Yersinia pseudotuberculosis Type III Secretion System Activity Following Iron Starvation and Anaerobic Growth
Published on: May 31, 2024
Regulation of the Yersinia pseudotuberculosis Type III Secretion System by the CpxAR Two-Component System
Karen Hug1, Erin Mettert2, Melissa Estrada Escobar1
1Department of Microbiology & Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA.
Molecular Microbiology
|May 25, 2026
Summary
The CpxAR system negatively regulates the Yersinia pseudotuberculosis type III secretion system (T3SS) indirectly. Deleting ompR increased T3SS expression, revealing complex two-component system regulation.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- The type III secretion system (T3SS) is crucial for virulence in Gram-negative pathogens.
- T3SS expression is tightly regulated by environmental signals, including cell envelope stress.
- The CpxAR two-component system is known to negatively regulate the Yersinia pseudotuberculosis Ysc T3SS, but the mechanism is not fully understood.
Purpose of the Study:
- To elucidate the mechanism by which the CpxAR two-component system regulates the Yersinia pseudotuberculosis Ysc T3SS.
- To identify the specific factors involved in CpxAR-mediated repression of T3SS expression.
Main Methods:
- Genetic manipulation of CpxAR activity and regulatory genes in Yersinia pseudotuberculosis.
- Analysis of Ysc T3SS and LcrF expression levels.
- Whole-genome transcriptome analysis (RNA-Seq).
Main Results:
- Constitutive CpxAR activity reduced Ysc T3SS and LcrF expression, confirming negative regulation.
- CpxR did not directly bind to the lcrF regulatory region, indicating indirect control.
- Transcriptome analysis revealed multiple differentially expressed genes, including potential regulatory factors, but no single gene explained the repression.
- Deletion of ompR resulted in increased LcrF and T3SS expression, highlighting the role of the OmpR/EnvZ system.
Conclusions:
- The CpxAR system likely regulates the Ysc T3SS through multiple indirect pathways.
- The OmpR/EnvZ two-component system plays a significant role in modulating Ysc T3SS expression.
- The regulation of the Ysc T3SS by two-component systems is more intricate than previously recognized.
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