G624T/G626S reduces the binding of TcdB1 to HeLa FZD1/2/7^–/–cells.

(A) Confocal images showed that fluorescent-labeled TcdB (red) robustly bound to the surface of the HeLa WT cells, while the binding of TcdB1^G624T/G626S was significantly reduced. The nuclei were stained by DAPI (blue). DIC, differential interference contrast. Scale bar, 50 μm. (B) Changes of the relative resistance of mutants G624T and G626S compared to the WT TcdB1 in the HeLa CSPG4^–/–and FZD1/2/7^–/–cells were shown in a bar chart. (Error bars indicate mean±s.d., n = 6, *P<0.001 versus TcdB1, student’s t-test).

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