Related Experiment Video
Updated: Jun 27, 2026
Quantifying Yersinia pseudotuberculosis Type III Secretion System Activity Following Iron Starvation and Anaerobic Growth
Published on: May 31, 2024
Targeting type III secretion in Yersinia pestis
Ning J Pan1, Michael J Brady, John M Leong
1Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, 01655, USA.
Abstract:
Yersinia pestis, the causative agent of plague, utilizes a plasmid-encoded type III secretion system (T3SS) to aid it with its resistance to host defenses. This system injects a set of effector proteins known as Yops (Yersinia outer proteins) into the cytosol of host cells that come into contact with the bacteria. T3SS is absolutely required for the virulence of Y. pestis, making it a potential target for new therapeutics. Using a novel and simple high-throughput screening method, we examined a diverse collection of chemical libraries for small molecules that inhibit type III secretion in Y. pestis. The primary screening of 70,966 compounds and mixtures yielded 421 presumptive inhibitors. We selected eight of these for further analysis in secondary assays. Four of the eight compounds effectively inhibited Yop secretion at micromolar concentrations. Interestingly, we observed differential inhibition among Yop species with some compounds. The compounds did not inhibit bacterial growth at the concentrations used in the inhibition assays. Three compounds protected HeLa cells from type III secretion-dependent cytotoxicity. Of the eight compounds examined in secondary assays, four show good promise as leads for structure-activity relationship studies. They are a diverse group, with each having a chemical scaffold not only distinct from each other but also distinct from previously described candidate type III secretion inhibitors.
Insights
Researchers screened thousands of chemicals to find inhibitors of the Yersinia pestis type III secretion system (T3SS), a key virulence factor in plague. Four novel compounds effectively blocked T3SS activity without harming bacteria, offering promising leads for new anti-plague therapies.
Area of Science:
- Microbiology
- Bacteriology
- Pathogen Virulence Mechanisms
Background:
- Yersinia pestis causes plague and uses a type III secretion system (T3SS) to inject Yersinia outer proteins (Yops) into host cells.
- The T3SS is essential for Y. pestis virulence, making it a critical target for developing novel anti-plague therapeutics.
Purpose of the Study:
- To identify small molecules that inhibit the Y. pestis T3SS using a high-throughput screening approach.
- To evaluate the efficacy and specificity of identified inhibitors against Yop secretion and bacterial cytotoxicity.
Main Methods:
- A high-throughput screen of 70,966 chemical compounds was performed to identify inhibitors of Y. pestis T3SS.
- Presumptive inhibitors underwent secondary assays to confirm Yop secretion inhibition, assess cytotoxicity, and evaluate effects on bacterial growth.
Main Results:
- 421 presumptive inhibitors were identified, with eight selected for further analysis.
- Four compounds demonstrated effective inhibition of Yop secretion at micromolar concentrations.
- Three of these compounds protected HeLa cells from T3SS-dependent cytotoxicity, and none inhibited bacterial growth at tested concentrations.
Conclusions:
- Four novel chemical scaffolds were identified as promising leads for Y. pestis T3SS inhibitor development.
- These compounds represent a distinct chemical class compared to previously described inhibitors.
- Further structure-activity relationship studies are warranted to develop potential anti-plague therapeutics.
More Related Videos
Related Concept Videos
01:24Plague
01:17Gram-negative Bacterial Protein Secretion Systems
01:28Regulation of Bacterial Virulence
01:20Determinants of Bacterial Pathogenicity and Virulence
01:28Gene Regulation in Microbial Communities: Quorum Sensing
01:12Bacterial Toxins