31P NMR studies of intracellular pH and phosphate metabolism during cell division cycle of Saccharomyces cerevisiae

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 78; no. 4; pp. 2125 - 2129
• Main Authors: Gillies, R.J, Ugurbil, K, Hollander, J.A. den, Shulman, R.G
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01-04-1981; National Acad Sciences
• Subjects: Biochemistry; Cell Cycle; Cell division; Chemical suspensions; Cultured cells; DNA - biosynthesis; Food Deprivation; Hydrogen-Ion Concentration; isotopes; Magnetic Resonance Spectroscopy; Oxygen; Phosphates; Phosphates - metabolism; phosphorus; Polyphosphates; Polyphosphates - metabolism; Refeeding; Saccharomyces cerevisiae - physiology; Starvation; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.78.4.2125

We have analyzed changes in intracellular pH and phosphate metabolism during the cell cycle of Saccharomyces cerevisiae (NCYC 239) by using high-resolution31P NMR spectroscopy. High-density yeast cultures (2× 108cells per ml) were arrested prior to ``start'' by sequential glucose deprivation, after which they synchronously replicated DNA and divided after a final glucose feeding. Oxygenation of arrested cultures in the absence of glucose led to increased levels of sugar phosphates and ATP and an increase in intracellular pH. However, these conditions did not initiate cell cycle progression, indicating that energization is not used as an intracellular signal for initiation of the cell division cycle and that the cells need exogenous carbon sources for growth. Glucose refeeding initiated an alkaline intracellular pH transient only in the synchronous cultures, showing that increased intracellular pH accompanies the traversal of start. Changes in phosphate flow and utilization also were observed in the synchronous cultures. In particular, there was increased consumption of external phosphate during DNA synthesis. When external phosphate levels were low, the cells consumed their internal polyphosphate stores. This shows that, under these conditions, polyphosphate acts as a phosphate supply.