Intracellular trehalose is neither necessary nor sufficient for desiccation tolerance in yeast

Abstract

Trehalose is thought to be important for desiccation tolerance in a number of organisms, including Saccharomyces cerevisiae, but there is limited in vivo evidence to support this hypothesis. In wild-type yeast, the degree of desiccation tolerance has been shown previously to increase in cultures after diauxic shift and also in exponential-phase cultures after exposure to heat stress. Under both these conditions, increased survival of desiccation correlates with elevated intracellular trehalose concentrations. Our data confirm these findings, but we have tested the apparent importance of trehalose using mutant strains with a deleted trehalose-6-phosphate synthase gene (tps1Delta). Although tps1Delta strains do not produce trehalose, they are nevertheless capable of desiccation tolerance, and the degree of tolerance also increases after diauxic shift or heat stress, albeit slightly less than in the wild type. Conversely, when wild-type yeast is subjected to osmotic stress, mid-exponential-phase cultures produce high concentrations of intracellular trehalose but show little improvement in desiccation tolerance. These results show that there is no consistent relationship between intracellular trehalose levels and desiccation tolerance in S. cerevisiae. Trehalose seems to be neither necessary nor sufficient for, although in some strains might quantitatively improve, survival of desiccation, suggesting that other adaptations are more important.

Gene families and evolution of trehalose metabolism in plants

“…Yeast (Saccharomyces cerevisiae) is another desiccation-tolerant organism that accumulates large amounts of trehalose. However, a study of yeast mutants that cannot synthesise trehalose found that the cells were still able to survive desiccation, whereas induction of trehalose accumulation by osmotic stress did not improve desiccation tolerance (Ratnakumar and Tunnacliffe 2006). These results, and some previous observations on rotifers (Tunnacliffe and Lapinski 2003), suggest that trehalose accumulation is neither necessary nor sufficient on its own for desiccation tolerance in these organisms, and call into question its role in trehaloseaccumulating resurrection plants.…”

Metabolic engineering of Saccharomyces cerevisiae for improvement in stresses tolerance

“…22,26,27 In yeast, trehalose level is low under favorable growth condition but is induced by environmental stresses. However, Ratnakumar and Tunnacliffe 28 suggested that there was no consistent relationship between intracellular trehalose concentration and desiccation tolerance in S. cerevisiae. In our previous study, 25 SCTDN (S. cerevisiae with overexpression of tps1 gene and deletion of nth1 gene) showed not only the highest accumulated intracellular trehalose but the greatest tolerance under stress conditions compare with SCT (S. cerevisiae with overexpression of tps1 gene) and wild strain.…”

Trehalose in Three Species of Desiccation Tolerant Tardigrades~!2009-10-14~!2010-01-29~!2010-04-21~!

“…However, it is clear that trehalose is not a necessary component to obtain desiccation tolerance, since there are desiccation tolerant organisms that lack this sugar completely [13]. In addition, while a number of studies have documented a beneficial effect of trehalose in vitro (e.g., [19]), the role of trehalose in vivo in anhydrobiotic organisms is still unclear, and the correlation between desiccation tolerance and trehalose level in, e.g., yeast is not consistent [20]. Recent studies on desiccation tolerance have also emphasized the potential role of stress proteins and their possible complementary or synergistic role together with other compounds such as sugars [12,21,22].…”