FIGURE 4.

All quinones of E. coli can both reduce (activate) and oxidize (inactivate) ArcAB/A. ArcA∼P Phos-Tag Western Blot of E. coli strain used in this study. The lower band represents ArcA while the upper band represents ArcA∼P, which is slowed down by the Phos-Tag gel during electorphoresis. The first two lanes are reserved for the ArcA standard, and in-vitro phosphorylated ArcA, respectively. P indicates the pre-culture and the other lanes the sampling time (min). The bar on top of (A–D) indicates N₂ (gray) or air (white) sparging. (A) E. coli MG1655, (B) E. coli AV34 (UQ-only), (C) E. coli DMK-only, (D) E. coli MK-only, (E) Graph of the phosphorylation level of ArcA in the different strains used in this study. The bar graphs shows the results of densitometric quantitation of the ArcA∼P/ArcA ratio. Data represent the average of three biologically independent replicates, error bars indicate the standard deviation.