title: Shigella dysenteriae 1 cytotoxin: periplasmic protein releasable by polymyxin B and osmotic shock.
abstract: Treatment of Shigella dysenteriae 1 either with the antibiotic polymyxin B or by osmotic shock resulted in the release of 80 to 90% of the cytotoxin activity of the organism. Under the conditions employed, the release of toxin activity was accompanied by the appearance of a periplasmic enzyme, 5'-nucleotidase. There was no significant release of cytoplasmic contents, assessed by measurement of glucose-6-phosphate dehydrogenase activity. The release of cytotoxin and 5'-nucleotidase by polymyxin B were both dependent on the duration of incubation with, and the concentration of, the antibiotic. In terms of specific activity (cytotoxin activity per milligram of protein), the polymyxin B and osmotic shock extracts were 20- to 30-fold more active than crude toxin preparation derived from a whole-cell lysate. The data strongly support a periplasmic location for Shiga cytotoxin and the utility of the polymyxin B extraction to obtain starting material for toxin purification.
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000378:metabolism*; D003603:Cytotoxins / Q000378:metabolism* / Q000633:toxicity; D003967:Diarrhea / Q000209:etiology; D004403:Dysentery / Q000209:etiology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D009708:Nucleotidases / Q000378:metabolism; D009997:Osmotic Pressure; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D012762:Shigella dysenteriae / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003603:Cytotoxins; D011113:Polymyxins; D009708:Nucleotidases; D011112:Polymyxin B