Structure activity relationships of an exotoxin of Pseudomonas aeruginosa

M. L. Vasil, D. Kabat, B. H. Iglewski

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61 Scopus citations


The relation of the structure of P. aeruginosa exotoxin A (PA toxin) to its enzymatic activity (adenosine 5'-diphosphate-ribosyl transferase) in vitro and to its toxicity in vivo was examined. PA toxin is produced as a single polypeptide chain with a molecular weight of about 71,500. PA toxin is produced by Pseudomonas as a toxic proenzyme that lacks enzymatic activity. Adenosine 5'-diphosphate- ribosyl transferase activity is expressed when the molecule is denatured and reduced or when it is cleaved by Pseudomonas proteases to yield an enzymatically active 27,000-dalton fragment (fragment a). A 45,000-dalton protein is tentatively identified as the enzymatically inactive fragment b of PA toxin. Enzymatically active forms of the toxin lack toxicity for mouse L-cells or mouse lethality. Thus, it is concluded that the native toxin proenzyme is required for toxicity and that a structural rearrangement must precede its intracellular activity.

Original languageEnglish (US)
Pages (from-to)353-361
Number of pages9
JournalInfection and Immunity
Issue number1
StatePublished - 1977
Externally publishedYes

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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