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Interaction of purified leukocidin from Pseudomonas aeruginosa with Bovine polymorphonuclear leukocytes
Abstract:
The interaction of purified leukocidin from Pseudomonas aeruginosa, strain 158, with polymorphonuclear leukocytes of cattle (PMLC) was studied by using 125I-labeled toxin. According to the Scatchard plot, PMLC offered two binding sites for leukocidin: one at the surface of the plasma membrane, and a second one that presumably became accessible to the toxin in the course of the cytotoxic action. Toxin once fixed to PMLC at 37 C could not be detached from the cells by either chemical or mechanical treatment. However, active leukocidin was liberated if it was bound to PMLC at 4 C and the temperature of the cell suspension was subsequently increased to 37 C. In the presence of Ca2+, the velocity of toxin fixation was accelerated and the rate of fixation was increased. Preliminary investigations on the identification of the leukocidin-binding material indicated the leukocidin receptor to be an integral protein of the plasma membrane.
Insights
Pseudomonas aeruginosa leukocidin binds to two sites on cattle polymorphonuclear leukocytes (PMLC). Binding is temperature-dependent, with calcium ions accelerating leukocidin fixation to its membrane protein receptor.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen that produces leukocidins, toxins that target host immune cells.
- Understanding the interaction between bacterial toxins and host cells is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the binding characteristics of purified Pseudomonas aeruginosa leukocidin to cattle polymorphonuclear leukocytes (PMLC).
- To identify the nature of the leukocidin receptor on PMLC.
Main Methods:
- Utilized 125I-labeled leukocidin for binding studies.
- Employed Scatchard plot analysis to determine binding kinetics and receptor sites.
- Investigated the effect of temperature and calcium ions on toxin-cell interaction.
- Performed preliminary studies to identify the leukocidin-binding material.
Main Results:
- Cattle PMLC possess two distinct binding sites for leukocidin.
- One binding site is on the plasma membrane surface; a second becomes accessible during cytotoxic action.
- Leukocidin bound at 37°C is irreversibly attached, while binding at 4°C allows liberation upon temperature increase.
- Calcium ions (Ca2+) enhance the velocity and rate of leukocidin fixation.
- Preliminary data suggest the receptor is an integral plasma membrane protein.
Conclusions:
- Leukocidin exhibits specific, multi-site binding to cattle PMLC, influenced by temperature and calcium.
- The leukocidin receptor is likely an integral membrane protein, providing insights into bacterial toxin-host cell interactions.