FIG. 6.

Zinc uptake into everted membrane vesicles is dependent upon ZitB: accumulation of ⁶⁵Zn²⁺ with 5 μM ZnCl₂ in everted membrane vesicles of E. coli strain GR362 carrying the pASK-IBA3 expression vector with zitB inserted (•), with zitB inserted in the presence of 10 μM FCCP (▪), or without zitB (○). Uptake was initiated at zero time by addition of 5 mM NADH, and vesicles were captured by filtration through a 0.2-μm-pore-size filter every 30 s for 2.5 min. ⁶⁵Zn accumulation was determined by liquid scintillation analysis. Identical measurements obtained in the absence of NADH were subtracted from the values obtained at the corresponding time points as background.