Fig. 5.

In vitro Cd binding, tolerance and accumulation assay of ΔSpBnPDFL in E. coli. a In vitro Cd binding assay. TF represents the E. coli trigger factor protein that fused to the N-terminus of target proteins, and the secretion signal peptide (SP)-deleted BnPDFL (TF-ΔSpBnPDFL) were used to transform E. coli. The molar ratio of Cd against TF-ΔSpBnPDFL protein purified from E. coli cells grown with 100 μM CdCl₂ for 10 h was determined by ICP-MS. b Heterologous overexpression of ΔSpBnPDFL enhanced Cd tolerance in E. coli. Relative growth rates for E. coli strains expressing empty vector or ΔSpBnPDFL supplemented with 0, 200 μM CdCl₂ for 6 h. c Cd concentration in E. coli strains from (b) was determined by ICP-MS. Data are mean ± SD, n = 4. Significant differences were determined by Student’s t-test (**P < 0.01)