Energy Coupling Reactions of the Active Transport System for α-Aminoisobutyric Acid in Alkalophilic Bacillus no. 8-1

Abstract

The energy source and energy coupling reaction of the active transport system for α-aminoisobutyric acid (AIB) in alkalophilic Bacillus no. 8-1 were studied.
Various metabolites such as glucose and succinate served as substrates for respiration and AIB uptake. Glucose also stimulated the synthesis of ATP. Potassium cyanide inhibited both respiration and AIB uptake to the same extent but uncouplers or ionophores inhibited AIB uptake much more than respiration. Arsenate had no inhibitory effect on these activities.
The inhibition of AIB uptake by uncouplers or ionophores was recovered by the addition of glucose at 20mM concentration. The cellular ATP level was reduced by carbonylcyanide-m-chlorophenylhydrazone (CCCP) but this inhibition was also reversed by the addition of glucose.
These results suggest that a coupling reaction for AIB uptake is driven by energized membrane states.