The metabolic properties of acid soluble polyphosphates in Saccharomyces cerevisiae

Tripolyphosphate was found to be the predominant species of soluble polyphosphate in yeast. Evidence is presented which shows that under normal growth conditions tripolyphosphate had little or no turnover. The amounts of the various polyphosphates decreased as the chain length increased. Tetrapolyphosphate was shown to be synthesized more rapidly than tripolyphosphate. These observations suggest that short chain polyphosphates arise by degradation of longer chain length polyphosphates with tripolyphosphate the ultimate degradation product. During nitrogen starvation, the normal accumulation of tripolyphosphate rapidly ceased even though the cells continued normal growth for at least two hours. After the addition of L-amino acids or (NH4)2SO4 to nitrogen starved cells, there was a dramatic increase in the accumulation of tripolyphosphate and tetrapolyphosphate which occurred at the same time as the increase in growth rate. Implications of this result are discussed in terms of possible functions of polyphosphate.