Polyamine-sensitive magnesium transport in Saccharomyces cerevisiae

• Published in: Biochimica et biophysica acta Vol. 1194; no. 2; pp. 289 - 295
• Main Authors: Maruyama, T, Masuda, N, Kakinuma, Y, Igarashi, K
• Format: Journal Article
• Language: English
• Published: Netherlands 14.09.1994
• Subjects: Biological Transport - drug effects; cations; Cell Division; ion transport; magnesium; Magnesium - metabolism; polyamines; Polyamines - pharmacology; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; spermine; toxicity
• ISSN: 0006-3002; 1878-2434
• DOI: 10.1016/0005-2736(94)90311-5

In Saccharomyces cerevisiae we found a toxic effect of polyamines well-known metabolites important for cell proliferation; in magnesium-limited (50 micromolar Mg2+) synthetic medium, cell growth was severely inhibited by spermine, spermidine and putrescine in descending order. In conjunction with a decrease in the growth rate by the addition of 0.5 millimole spermine, the internal Mg2+ content decreased and the spermine content increased. When cell growth ceased, the Mg2+ content had finally decreased to about 40% of the value before the addition of spermine (120-130 nmol/mg dry weight), and the spermine content concomitantly increased 30-fold (from 1 to 30 nmol/mg dry weight); spermine 4+ apparently took the internal place of Mg2+ with a probable stoichiometry of 1:2. However, the total amount of Mg2+ retained in the cells remained constant even with the addition of spermine, suggesting that spermine blocks Mg2+ accumulation. In high (2 millimole) Mg2+ medium, cell growth was hardly affected by polyamines, and an exchange of spermine and Mg2+ was minimal. Energy-dependent Mg2+ uptake by whole cells was inhibited by spermine, spermidine and putrescine in a similar manner as the growth rates. On the other hand, Mg2+ inhibited spermine uptake. These results suggest that competition takes place between extracellular spermine and Mg2+ for their accumulations. It is thus clear that polyamine-sensitive Mg2+ transport system is indispensable for the physiology of this organism.