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Pseudomonas aeruginosa ExoT is a Rho GTPase-activating protein
R Krall1, G Schmidt, K Aktories
1Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, Wisconsin 53226, USA.
Abstract:
Transient intracellular expression of ExoT in CHO cells stimulated cell rounding and actin reorganization. Biochemical studies showed that ExoT was a GTPase-activating protein for RhoA, Rac1, and Cdc42. Together, these data show that ExoT interferes with Rho signal transduction pathways, which regulate actin organization, exocytosis, cell cycle progression, and phagocytosis.
Insights
The bacterial toxin ExoT disrupts host cell functions by interfering with Rho signaling pathways. This toxin causes cell rounding and actin reorganization, impacting cell cycle and phagocytosis.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Bacterial toxins can significantly alter host cell physiology.
- Rho GTPases are critical regulators of the actin cytoskeleton and other cellular processes.
Purpose of the Study:
- To investigate the effects of the bacterial toxin ExoT on host cell behavior.
- To elucidate the molecular mechanism by which ExoT influences cellular signaling.
Main Methods:
- Transient intracellular expression of ExoT in Chinese Hamster Ovary (CHO) cells.
- Biochemical assays to determine the enzymatic activity of ExoT.
Main Results:
- ExoT expression induced cell rounding and actin reorganization in CHO cells.
- ExoT demonstrated GTPase-activating protein (GAP) activity towards RhoA, Rac1, and Cdc42.
- These findings indicate ExoT's role in disrupting Rho signal transduction.
Conclusions:
- ExoT interferes with Rho-mediated pathways essential for actin organization.
- The toxin impacts fundamental cellular processes including exocytosis, cell cycle progression, and phagocytosis.