Inorganic phosphate transport inAcinetobacter lwoffi

Abstract

The transport of inorganic phosphate has been studied inAcinetobacter lwoffi JW11. During growth on excess phosphate, only one transport system was present, with an apparent Km of 1.4 μM. When cells were starved for phosphate, a second uptake system with an apparent Km of 110 nM was also synthesized. The two transport systems could be distinguished by differing sensitivities to the phosphate analogs arsenate and 2-aminoethylphosphonate. Both systems were inhibited by carbonylcyanidem-chlorophenylhydrazone, and to a lesser extent by Na azide. The high-affinity transport system was inactivated by osmotic shock treatment and by spheroplast formation. Preliminary evidence for a phosphate-binding protein in the osmotic shock fluid is presented. The isolation of a mutant constitutive for the high-affinity transport system is described.