Beeler T, Bruce K, Dunn T
Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
Biochim Biophys Acta. 1997 Jan 31;1323(2):310-8. doi: 10.1016/s0005-2736(96)00199-x.
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.
研究了酿酒酵母对细胞内镁离子（Mg2+）的调节作用。导致酿酒酵母最佳生长的Mg2+最低浓度约为30微摩尔，在约5微摩尔Mg2+时达到最大生长速率的一半。由于质膜的电势大于100毫伏，Mg2+跨质膜的被动平衡将提供足够的胞质Mg2+（0.1 - 1毫摩尔）。在含有1毫摩尔Mg2+的合成培养基中生长的细胞，其细胞总Mg2+约为400纳摩尔/毫克蛋白质，其中大部分与多磷酸盐、核酸和ATP结合。随着合成生长培养基中的Mg2+降至0.02毫摩尔，细胞总Mg2+降至约80纳摩尔/毫克蛋白质，但在含有1至100毫摩尔Mg2+的生长培养基中保持相对恒定。转移到无Mg2+培养基中的细胞通过利用液泡中的Mg2+储存继续生长。在向生长培养基中添加1毫摩尔Mg2+后，缺Mg2+的细胞以30分钟的半衰期补充液泡中的Mg2+储存。数据表明，胞质Mg2+通过调节Mg2+跨液泡膜和质膜的通量来维持。
