Figure 7.

Cir1 is an iron-containing protein. (A) E. coli cells were transformed with pET28 derivatives encoding Cir1^{Wild type (WT)}, Cir1^{C180A, C183A}, Cir1^{C308A, C311A}, or Cir1^{R320A, R321A}. Protein production was induced by the addition of 1 mM of IPTG for 3 hr at 37°. The cultures were centrifuged and cell pellets were photographed. (B) Cir1 purified from cells grown in a medium containing 1 mM IPTG (red), or in one containing 1 mM IPTG and 1 mM BPS (blue) was analyzed using UV-visible spectrophotometer. Cir1 purified from cells grown in the presence of 1 mM IPTG and 1 mM BPS, and treated with sodium dithionite (SDT; green) was also analyzed. (C) UV-visible absorption spectra of proteins purified from strains producing Cir1^WT (red) or Cir1^{C180A, C183A} (blue). (D) Iron content of the purified Cir1^WT and Cir1^{C180A, C183A} proteins was determined. Three biological replicates were analyzed. **P < 0.01.