Figure 1.

Bac protects human intestinal epithelial cells from intoxication with TcdB. (a) CaCo-2 cells were preincubated for 30 min in serum-containing medium with or without Bac (1 mM). TcdB (6 ng/ml) was added into the medium and cells were further incubated. For control (con), cells were left untreated. Representative pictures of the cells after 5 h of incubation are shown. The scale bar represents 50 μm. (b) Bac prevents Rac1 glucosylation by TcdB in living cells. CaCo-2 cells were preincubated at 37°C with 0, 0.3, 1, or 3 mM Bac and TcdA (6 ng/ml) was added. For control, cells were left untreated (con) or treated with 3 mM Bac in the absence of TcdB. After 5 h of incubation, cells were washed and lysed and the amount of nonglucosylated Rac1 was analyzed by Western blotting. Actin was detected in the same blot to confirm comparable protein loading.