Induction and Properties of the Citrate Transport System in Aerobacter aerogenes

Abstract

The mediated transport of citrate in Aerobacter aerogenes was studied. According to data obtained by examining the distribution of radioactive citrate at room temperature and at 0 C, a carrier system appears to be located on the membrane. The carrier system is inducible and very specific, not acting on the related compounds isocitrate and cis-aconitate. Induction required synthesis of both ribonucleic acid and protein as determined by starving auxotrophic mutants and by using specific inhibitors of protein synthesis. Citrate transport was inhibited by N -ethyl maleimide, dinitrofluorobenzene, and uranyl nitrate. A kinetic study of uranyl nitrate inhibition revealed that the inhibition of citrate transport was different from that of glucose penetration. Cyanide also discriminated citrate from glucose penetration inhibiting only the former. These last results suggested that energy is required for citrate penetration.