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Updated: Jun 12, 2026
Analysis of Yersinia enterocolitica Effector Translocation into Host Cells Using Beta-lactamase Effector Fusions
Published on: October 13, 2015
Identification and characterization of small-molecule inhibitors of Yop translocation in Yersinia pseudotuberculosis
Dana E Harmon1, Alison J Davis, Cynthia Castillo
1Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA.
Abstract:
Type three secretion systems (TTSSs) are virulence factors found in many pathogenic Gram-negative species, including the family of pathogenic Yersinia spp. Yersinia pseudotuberculosis requires the translocation of a group of effector molecules, called Yops, to subvert the innate immune response and establish infection. Polarized transfer of Yops from bacteria to immune cells depends on several factors, including the presence of a functional TTSS, the successful attachment of Yersinia to the target cell, and translocon insertion into the target cell membrane. Here we employed a high-throughput screen to identify small molecules that block translocation of Yops into mammalian cells. We identified 6 compounds that inhibited translocation of effectors without affecting synthesis of TTSS components and secreted effectors, assembly of the TTSS, or secretion of effectors. One compound, C20, reduced adherence of Y. pseudotuberculosis to target cells. Additionally, the compounds caused leakage of Yops into the supernatant during infection and thus reduced polarized translocation. Furthermore, several molecules, namely, C20, C22, C24, C34, and C38, also inhibited ExoS-mediated cell rounding, suggesting that the compounds target factors that are conserved between Pseudomonas aeruginosa and Y. pseudotuberculosis. In summary, we have identified 6 compounds that specifically inhibit translocation of Yops into mammalian cells but not Yop synthesis or secretion.
Insights
Researchers identified six compounds that specifically block the translocation of Yersinia outer proteins (Yops) into host cells. These molecules inhibit Yop delivery without affecting Yop synthesis or secretion, offering potential therapeutic targets.
Area of Science:
- Microbiology
- Immunology
- Molecular Biology
Background:
- Type three secretion systems (TTSSs) are crucial virulence factors in Gram-negative pathogens like Yersinia spp.
- Yersinia pseudotuberculosis utilizes TTSS to translocate Yersinia outer proteins (Yops) to subvert host immune responses.
- Effective Yop translocation depends on TTSS function, bacterial attachment, and translocon insertion into host cell membranes.
Purpose of the Study:
- To identify small molecules that specifically inhibit Yop translocation into mammalian cells.
- To find compounds that block Yersinia virulence factor delivery without impacting essential bacterial processes.
Main Methods:
- A high-throughput screening assay was utilized to identify inhibitory compounds.
- Assays assessed the impact of compounds on Yop translocation, synthesis, secretion, and bacterial adherence.
- Compounds were tested for their effect on ExoS-mediated cell rounding in Pseudomonas aeruginosa.
Main Results:
- Six compounds were identified that inhibit Yop translocation without affecting TTSS component synthesis, assembly, or secretion.
- One compound (C20) reduced bacterial adherence to target cells.
- Several compounds (C20, C22, C24, C34, C38) inhibited ExoS-mediated cell rounding, indicating conserved targets.
Conclusions:
- The identified compounds specifically inhibit Yop translocation, not Yop synthesis or secretion.
- These small molecules represent potential therapeutic agents against Yersinia infections by disrupting virulence factor delivery.
- The compounds may target conserved mechanisms relevant to other bacterial pathogens like Pseudomonas aeruginosa.
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