Characterization of a lysine-specific active transport system in Rickettsia prowazeki

Abstract

Rickettsia prowazeki possesses an active transport system for lysine with a Kt of influx of 1 muM. Extraction and chromatographic analysis of the accumulated labeled material show the material to be lysine rather than a derivative. This intracellular lysine pool can be exchanged with external unlabeled substrates for at least 10 min; The lysine analogues L-aminoethyl cysteine, N-methyl lysine, hydroxylysine, and D-lysine competitively inhibit uptake of L-lysine, but cadaverine, diaminopimelate, arginine, ornithine, and epsilon-aminocaproate do not. Accumulation of lysine can be inhibited by the energy poisons potassium cyanide, triphenylmethyl phosphonium bromide, and 2,4-dinitrophenol. The effect of potassium cyanide, but not 2,4-dinitrophenol or triphenylmethyl phosphonium bromide, can be overcome by adenosine 5'-triphosphate. Both energy-dependent influx and energy-independent efflux are inhibited by the sulfhydryl reagents N-ethyl maleimide and p-chloromercuriphenyl sulfonic acid.