ACTIVE TRANSPORT OF MAGNESIUM IN <i>Escherichia coli</i>

Abstract

Magnesium-28 is accumulated by cells of Escherichia coli by a process that is temperature-dependent and inhibited by dinitrophenol and cyanide. The rate of uptake of magnesium is concentration-dependent, with a "K(m)" of about 5 x 10(-4)M in tryptone broth. There is evidence for cellular control over this rate. The magnesium accumulation system is specific, since neither potassium nor calcium (nor apparently manganese) competes with magnesium for cellular uptake. The magnesium that is accumulated by the cells can be released by treatment with toluene and partially exchanges with excess exogenous magnesium.