A dual role for intracellular trehalose in the resistance of yeast cells to water stress

It is well known that yeast cells survive environmental stresses such as de siccation and freezing and there is evidence that these phenomena may be re lated to the presence of trehalose in the cells. However, the molecular mec hanism by which trehalose might exert an influence on cell functions remain s unknown. In this report, thermogravimetry and differential thermal analys is were used to estimate the amount of bound water in yeast cells. It is sh own that when the trehalose content is greater than 2-3% of the cell dry we ight, the amount of bound water is drastically decreased and the viability of the dried cells is increased. This implies that a major portion of the b ound water is replaced by trehalose. In addition, measurements of the NMR s pin-lattice relaxation time of the intracellular water protons show that tr ehalose acts as a water-structuring agent in hydrated yeast cells. This dua l role is essential for high resistance to water stress in yeast cells. (C) 1999 Academic Press.