Regulation of cellular Mg2+ by Saccharomyces cerevisiae.
Regulation of cellular Mg2+ by S. cerevisiae was investigated. The minimal concentration of Mg2+ that results in optimal growth of S. cerevisiae is about 30 microM and a half-maximum growth rate is attained at about 5 microM Mg2+. Since the plasma membrane has an electrical potential greater than 100 mV, passive equilibration of Mg2+ across the plasma membrane would provide sufficient cytosolic Mg2+ (0.1-1 mM). The total cellular Mg2+ of cells grown in synthetic medium containing 1 mM Mg2+ is about 400 nmol/mg protein, most of which is bound to polyphosphate, nucleic acids, and ATP. Total cellular Mg2+ decreases to about 80 nmol/mg protein as the Mg2+ in synthetic growth medium is reduced to 0.02 mM, but remains relatively constant in growth medium containing 1 to 100 mM Mg2+. Cells shifted into Mg(2+)-free medium continue to grow by utilizing the vacuolar Mg2+ stores. Mg(2+)-starved cells replenish vacuolar Mg2+ stores with a halftime of 30 min. following the addition of 1 mM Mg2+ to the growth medium. The data indicate that cytosolic Mg2+ is maintained by the regulation of Mg2+ fluxes across both the vacuolar and plasma membranes.
Beeler
T
T
Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
Bruce
K
K
Dunn
T
T
D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D011122:Polyphosphates; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
D011122:Polyphosphates; D008274:Magnesium; D002118:Calcium