The specific requirement for sodium chloride for the active uptake of l-glutamate by Halobacterium salinarium

Abstract

Uptake of L-glutamate by H. salinarium is dependent on high concentrations of sodium chloride in the environment. When the sodium chloride is replaced by isomolar concentrations of potassium chloride, sodium acetate or potassium acetate, only negligible uptake occurs. Most of the glutamate taken up can be shown to be in the cells in the free state and at a concentration of at least 50 times that in the medium. Sodium chloride is therefore required for an active transport of the glutamate into the cells. The question whether sodium chloride is essential for the actual migration of glutamate across the cell envelope or for the mechanism supplying energy for this migration is discussed on the basis of experiments on endogenous respiration and with inhibitors.