Accumulation of Polyphosphates and Expression of High Molecular Weight Exopolyphosphatase in the Yeast Saccharomyces cerevisiae

---

T. V. Kulakovskaya^*, N. A. Andreeva, L. V. Trilisenko, S. V. Suetin, V. M. Vagabov, and I. S. Kulaev

Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 142292 Pushchino, Moscow Region, Russia; fax: (7-095) 923-3602; E-mail: alla@ibpm.pushchino.ru

^* To whom correspondence should be addressed.

Received July 22, 2004; Revision received August 31, 2004

---

The effect of cultivation time and concentration of inorganic phosphate (P_i) in the culture medium on the accumulation of polyphosphates (polyP) and the activity of two cytosolic exopolyphosphatases of the yeast Saccharomyces cerevisiae was studied: an exopolyphosphatase of 40 kD encoded by PPX1 and a high molecular weight exopolyphosphatase encoded by another gene. Depletion of polyP in the cells on P_i starvation is a signal factor for the accumulation of polyP after the subsequent addition of 5-20 mM P_i and glucose to the cells or spheroplasts. A high activity of both exopolyphosphatases does not prevent the accumulation of polyP. The expression of the high molecular weight exopolyphosphatase is due to the acceleration of metabolism in cells that have reached the stage of growth deceleration on the addition of P_i and glucose or complete culture medium. This process may occur independently from the accumulation of polyP. The activity of exopolyphosphatase PPX1 depends less on the mentioned factors, decreasing 10-fold only under conditions of phosphate surplus at the stationary growth stage.

---

KEY WORDS: polyphosphates, exopolyphosphatase, cytosol, growth stage, phosphate, phosphate surplus, yeast, Saccharomyces cerevisiae

---