FIG 2.

Antiport activity of M. acetivorans MrpA in everted membrane vesicles of E. coli strains. The assay mixtures contained 50 to 75 μg of vesicle protein in 2 ml of 50 mM Bis-Tris propane buffer at pH 8.0. (A) Strain K-12. (B) Strain mrpA EP432. (C) Strain mrpA KNabc. (D) Strain EP432. The traces are representative of the results of 4 independent experiments. The arrows indicate (i) the time scale (50s), (ii) when respiration was initiated with 0.5 mM NADH (NADH), (iii) when quenching reached steady state and a nonsaturating 50 mM NaCl was added (NaCl), and (iv) when 5 μM CCCP was added (CCCP). ΔF, relative change in fluorescence.