Appearance of the Na⁺‐motive terminal oxidase in Bacillus FTU grown under three different conditions lowering the Δ\̄gm_H+ level

Abstract

The terminal oxidases and coupled Na' transport have hwn studied in intact cells and inside-out subccllucar vesicles of alkalo-and halotolerant Burihs FTU grown under different conditions. Cells grown at pH 7.5 arc shown to possess a system of respiration-dependent Nn' transport which is (i) inhibited by protonophorous uncoupler and (ii) activated by the d&discharging agent valinomycin. suggesting that the Na' transport is due to cooperation of the El+-molive oxidasc and Na+/H+ anliporter. On the other hand, growth under conditions lowering the Ml,-Ievcl, namely (i) pH 8.6, (ii) pH 7.5 in the presence of protonophorc. and (iii) pH 7.5 in the presence of low cyanide concentrations results in appearance ot-terminal oxidasc-supported Na* transport which is stimulated by protonophores (the Na'motive oxidase). In all three cases, the appearance of ascorbate (+ TMPD) oxidation resistant to low and sensitive to high cyanide concentrations was found LO occur. It is concluded that not only alkaline pH but also other conditions which lower dp ,,+ can cause substitution of Na+ for H' as a coupling ion.

Kinetics of CO binding to putative Na+‐motive oxidases of the o‐type from Bacillus FTU and of the d‐type from Escherichia coli

“…As shown in our laboratory, membrane vesicles from the E. coli mutant containing only the d-type oxidase [5] and those from Bat. FTU grown under low 4iir.i+ conditions [6] were competent in Na' transport when TMPD and ascorbate were used as electron donors. The process was resistant to low concentrations of KCN [5,7,8].…”

Kinetics of CO binding to H+‐motive oxidases of the caa3‐type from Bacillus FTU and of the o‐type from Escherichia coli

“…As shown in our laboratory, membrane vesicles from the E. coli mutant containing only the d-type oxidase [5] and those from Bat. FTU grown under low 4iir.i+ conditions [6] were competent in Na' transport when TMPD and ascorbate were used as electron donors. The process was resistant to low concentrations of KCN [5,7,8].…”