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Variation in lipid A structure in the pathogenic yersiniae
Roberto Rebeil1, Robert K Ernst, Brian B Gowen
1Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th St., Hamilton, MT 59840, USA.
Molecular Microbiology
|May 29, 2004
Summary
Yersinia bacteria alter their lipid A structure in response to temperature changes. This modification affects the immune response, with lower temperatures producing a more immunostimulatory lipopolysaccharide (LPS).
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- The genus Yersinia includes significant human pathogens like Yersinia pestis, Yersinia pseudotuberculosis, and Yersinia enterocolitica.
- Lipid A is a crucial component of lipopolysaccharide (LPS), responsible for the molecule's endotoxic activity and interaction with the host immune system.
Purpose of the Study:
- To investigate the impact of growth temperature shifts on the lipid A structure of Yersinia species.
- To determine how temperature-induced changes in lipid A acylation affect the stimulation of human immune cells.
Main Methods:
- Culturing Yersinia species (Y. pestis, Y. pseudotuberculosis, Y. enterocolitica) at different temperatures (37°C and 21°C).
- Analyzing the acyl group composition of lipid A from lipopolysaccharide (LPS) using chromatographic techniques.
- Assessing the immunostimulatory potential of synthesized lipid A by measuring tumor necrosis factor-alpha (TNF-α) secretion from human monocytes.
Main Results:
- Yersinia species exhibited temperature-dependent alterations in lipid A acylation patterns.
- At 37°C, Yersinia produced predominantly tetra-acylated lipid A, which showed minimal TNF-α induction in monocytes.
- At 21°C, Yersinia synthesized more complex, hexa-acylated lipid A, which potently stimulated TNF-α secretion.
Conclusions:
- Yersinia species conserve a mechanism to produce less immunostimulatory LPS at mammalian host temperatures (37°C).
- This temperature-dependent modulation of lipid A structure is a potential virulence factor, aiding bacterial survival and pathogenesis.
- Species-specific variations in lipid A may contribute to differing Yersinia life cycles and pathogenicity.