Restoration of active calcium transport in vesicles of an Mg 2+-ATPase mutant of [formula omitted] by wild-type Mg 2+-ATPase

Abstract

Strain NR70, a mutant of E. coli lacking the Mg 2+-adenosine triphosphatase (E.C. 3.6.1.3.) was previously shown to be defective in amino acid and sugar transport in whole cells and right-side-out membrane vesicles. It is shown here that the mutant is also deficient in the uptake of calcium into inverted membrane vesicles. Treatment of inverted vesicles from the wild-type strain with ethylenediamine tetraacetate removes the Mg 2+-adenosine triphosphatase and results in an inability to transport calcium. Addition of a crude fraction containing the wild-type Mg 2+-adenosine triphosphatase restores active uptake of calcium both to vesicles from the mutant and depleted vesicles from the wild-type.