# BASIS FOR CELLULAR SUSCEPTIBILITY TO BACTERIAL TOXINS

> **NIH NIH R01** · UNIVERSITY OF CINCINNATI · 1990 · $181,914

## Abstract

Diphtheria toxin (DT) and pseudomonas exotoxin A (PE) are potent
cytotoxic proteins produced by Corynebacterium diphtheriae and
Pseudomonas aeruginosa.  Both toxins are virulence factors for the
organisms secreting them, as well as serving as useful probes in
Cell Biology.  Both proteins exert their toxic effect by stopping
protein synthesis in mammalian cells; both are enzymes and act by
ADP ribosylation of cytoplasmic elongation factor 2.  The
structures of these two enzymatically identical proteins however
are different.

In order to exert a biological effect on sensitive cells, both
toxins bind to specific cell surface receptors, are internalized
via coated areas into endosomes, delivered to the Golgi region and
then to lysosomes.  During this intracellular trafficking the
toxins are converted to an enzyme active form, presumably in
endosomes or Golgi associated vesicles.  The site of escape into
the cytoplasm is unknown.

In the next grant period, we propose to:
(1) Definitively define the sites and mechanisms for processing
both PE and DT in sensitive cells, and determine if they are
similar or different in resistant cells.  This understanding will
allow us to determine if the manner in which a mammalian cell
handles a toxin dictates the cell's susceptibility to that toxin.
(2) Isolate and characterize the receptor for PE on mouse LM
fibroblasts.  Once the receptor has been purified, partially
sequenced, and antibodies made to it, the cDNA for the receptor can
be cloned.
(3) Define the intracellular pathway for the PE receptor in LM
cells.  We will determine if receptor follows the same pathway in
the presence and absence of PE, and the site of toxin-receptor
dissociation.

Experiments on toxin trafficking and processing involve subcellular
fractionation and identification of toxin by ELISA, or Induction
of ADP ribosyl-transferase activity with gradient fractions.  Toxin
movement on the ultrastructural level will be followed using
biotinyl-toxin-streptavidin-gold, or by pre-embedding
immunochemical techniques.  Receptor movement will be characterized
both with electron microscopy and with biochemical probes.

## Key facts

- **NIH application ID:** 3127266
- **Project number:** 5R01AI017529-10
- **Recipient organization:** UNIVERSITY OF CINCINNATI
- **SAM.gov UEI:** DZ4YCZ3QSPR5
- **Principal Investigator:** CATHARINE B SAELINGER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $181,914
- **Award type:** 5
- **Project period:** 1980-12-01 → 1992-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3127266

## Citation

> US National Institutes of Health, RePORTER application 3127266, BASIS FOR CELLULAR SUSCEPTIBILITY TO BACTERIAL TOXINS (5R01AI017529-10). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3127266. Licensed CC0.

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