Pseudomonas and diphtheria toxins (PE and DT) are virulence factors produced by Pseudomonas aeruginosa and Corynebacterium diphtheriae respectively. These distinct protein toxins both inhibit mammalian cell protein synthesis by inactivating cytoplasmic elongation factor 2. Evidence from our laboratory shows that PE and DT enter sensitive cells by receptor mediated endocytosis, following clustering over specialized clathri-coated areas on the cell surface, move in membrane bound vesicles to the Golgi region and then to the lysosomes. This pathway is essential for expression of toxicity.
The specific aims of the research are: l. To definitively characterize organelles involved in intracellular processing of DT and PE. 2. To determine the site of conversion from proenzyme to enzyme active form. 3. To initiate purification and characterization of DT and PE binding proteins. 4. To visualize toxin-receptor uncoupling, and entry of toxin into cytoplasm. Biochemical and electron microscopic studies will be carried out in parallel to compare the movement of PE and DT in both sensitive and resistant cells. Subcellular fractionation studies also will be used to localize iodinated toxins in cells. Agents which stop the intoxication process at different steps will be used to determine where the toxins are activated and where they, or an enzyme active fragment, enter the cell cytoplasm. Immunocytochemistry will be used to determine where toxin and ligand dissociate, and toxin enters the cytoplasm.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI017529-06
Application #
3127263
Study Section
Bacteriology and Mycology Subcommittee 1 (BM)
Project Start
1980-12-01
Project End
1988-06-30
Budget Start
1986-07-01
Budget End
1987-06-30
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Type
Schools of Medicine
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Mucci, D; Forristal, J; Strickland, D et al. (1995) Level of receptor-associated protein moderates cellular susceptibility to pseudomonas exotoxin A. Infect Immun 63:2912-8
Kounnas, M Z; Morris, R E; Thompson, M R et al. (1992) The alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein binds and internalizes Pseudomonas exotoxin A. J Biol Chem 267:12420-3
Morris, R E; Ciraolo, G M; Saelinger, C B (1992) Validation of the biotinyl ligand-avidin-gold technique. J Histochem Cytochem 40:711-21
Thompson, M R; Forristal, J; Kauffmann, P et al. (1991) Isolation and characterization of Pseudomonas aeruginosa exotoxin A binding glycoprotein from mouse LM cells. J Biol Chem 266:2390-6
Morris, R E; Ciraolo, G M; Saelinger, C B (1991) Gold enhancement of gold-labeled probes: gold-intensified staining technique (GIST). J Histochem Cytochem 39:1585-91
Forristal, J J; Thompson, M R; Morris, R E et al. (1991) Mouse liver contains a Pseudomonas aeruginosa exotoxin A-binding protein. Infect Immun 59:2880-4
Saelinger, C B; Morris, R E (1987) Intracellular trafficking of Pseudomonas exotoxin A. Antibiot Chemother 39:149-59
Morris, R E; Saelinger, C B (1986) Reduced temperature alters Pseudomonas exotoxin A entry into the mouse LM cell. Infect Immun 52:445-53
Saelinger, C B; Morris, R E; Foertsch, G (1985) Trafficking of Pseudomonas exotoxin A in mammalian cells. Eur J Clin Microbiol 4:170-4
Morris, R E; Gerstein, A S; Bonventre, P F et al. (1985) Receptor-mediated entry of diphtheria toxin into monkey kidney (Vero) cells: electron microscopic evaluation. Infect Immun 50:721-7