title: Purification and properties of Clostridium difficile cytotoxin B.
abstract: Toxin B, a potent cytotoxin produced by Clostridium difficile, was purified to homogeneity from 6-day broth cultures of a toxigenic isolate. Cytotoxin was purified approximately 4000-fold by sequential ammonium sulfate precipitation, DEAE-Sepharose chromatography, and high performance liquid chromatography on a Mono Q anion-exchange column. The molecular weight of reduced purified toxin was 50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, compared to 150,000 for unreduced toxin. Dose-response studies indicated that subpicogram concentrations of purified toxin caused rounding of approximately 20,000 IMR-90 fibroblasts. The phenomenon of cell rounding caused by toxin B was correlated with the ratio of globular to filamentous actin in fibroblasts as measured by two techniques. The toxin caused a significant increase in the ratio of globular to filamentous actin which was nearly completed prior to the onset of rounding. We conclude that cell rounding of fibroblasts exposed to toxin B is related to an increase in the ratio of globular to filamentous actin which is produced by small numbers of toxin molecules/cell.
mesh_terms: D000199:Actins / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000302:isolation & purification* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003850:Deoxyribonuclease I / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D007525:Isoelectric Focusing; D013997:Time Factors
chemical_list: D000199:Actins; D000596:Amino Acids; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C031815:toxB protein, Clostridium difficile; D003850:Deoxyribonuclease I