The content and chain length of polyphosphates from vacuoles of Saccharomyces cerevisiae VKM Y-1173

The content of inorganic polyphosphates (polyP) in vacuoles of the yeast Saccharomyces cerevisiae is 15% of the total cellular polyP. Over 80% of the vacuole polyP are in an acid-soluble fraction. It was first established by ³¹P-NMR spectroscopy that a polymeric degree (n) of two subfractions obtained by precipitation with Ba²⁺ in succession at pH 4.5 and 8.2 was approximately 20 ± 5 and 5 ± 2 residues of ortho-phosphoric acid, respectively. Under a deficit of phosphate (P_i) in the cultivation medium, the polyP content in vacuoles decreased 7-fold with the same drastic reduction of their content in the cell. Unlike intact yeast cells, where polyP overcompensation is observed after their transfer from phosphate-free to phosphate-containing medium, the vacuoles do not show this effect. The data indicate the occurrence of special regulatory mechanisms of polyP synthesis in vacuoles differing from those in the whole cell.