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Updated: May 22, 2026
Analysis of Yersinia enterocolitica Effector Translocation into Host Cells Using Beta-lactamase Effector Fusions
Published on: October 13, 2015
Vulnerabilities in Yersinia pestis caf operon are unveiled by a Salmonella vector
Ling Cao1, Timothy Lim, SangMu Jun
1Immunology and Infectious Diseases, Montana State University, Bozeman, Montana, USA.
Abstract:
During infection, Yersinia pestis uses its F1 capsule to enhance survival and cause virulence to mammalian host. Since F1 is produced in large quantities and secreted into the host tissues, it also serves as a major immune target. To hold this detrimental effect under proper control, Y. pestis expresses the caf operon (encoding the F1 capsule) in a temperature-dependent manner. However, additional properties of the caf operon limit its expression. By overexpressing the caf operon in wild-type Salmonella enterica serovar Typhimurium under a potent promoter, virulence of Salmonella was greatly attenuated both in vitro and in vivo. In contrast, expression of the caf operon under the regulation of its native promoter exhibited negligible impairment of Salmonellae virulence. In-depth investigation revealed all individual genes in the caf operon attenuated Salmonella when overexpressed. The deleterious effects of caf operon and the caf individual genes were further confirmed when they were overexpressed in Y. pestis KIM6+. This study suggests that by using a weak inducible promoter, the detrimental effects of the caf operon are minimally manifested in Y. pestis. Thus, through tight regulation of the caf operon, Y. pestis precisely balances its capsular anti-phagocytic properties with the detrimental effects of caf during interaction with mammalian host.
Insights
Yersinia pestis's F1 capsule enhances survival but can be detrimental. Overexpressing its caf operon in other bacteria, like Salmonella, significantly reduces virulence, suggesting tight regulation is key for Y. pestis.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Yersinia pestis utilizes its F1 capsule for virulence and host survival.
- The F1 capsule is a major immune target due to its large-scale secretion.
- The caf operon, encoding the F1 capsule, is temperature-dependent but has other expression-limiting factors.
Purpose of the Study:
- To investigate the role of the caf operon in bacterial virulence.
- To determine the impact of caf operon overexpression on Salmonella enterica serovar Typhimurium.
- To understand the regulatory mechanisms balancing virulence and self-harm in Y. pestis.
Main Methods:
- Overexpression of the caf operon in Salmonella Typhimurium using a potent promoter.
- Expression analysis of individual caf operon genes.
- Overexpression of the caf operon and its genes in Y. pestis KIM6+.
Main Results:
- Overexpression of the caf operon in Salmonella significantly attenuated virulence both in vitro and in vivo.
- Individual genes within the caf operon also attenuated Salmonella when overexpressed.
- Overexpression of the caf operon in Y. pestis confirmed its deleterious effects.
Conclusions:
- Tight regulation of the caf operon is crucial for Y. pestis to balance virulence and detrimental effects.
- Weak inducible promoters minimize the negative impacts of the caf operon in Y. pestis.
- The study highlights the importance of precise gene regulation in bacterial pathogenesis.
