Abstract
The disaccharide trehalose, which accumulates dramatically during heat shock and stationary phase in many organisms, enhances thermotolerance and reduces aggregation of denatured proteins. Here we report a new role for trehalose in protecting cells against oxygen radicals. Exposure of Saccharomyces cerevisiae to a mild heat shock (38 degrees C) or to a proteasome inhibitor (MG132) induced trehalose accumulation and markedly increased the viability of the cells upon exposure to a free radical-generating system (H(2)O(2)/iron). When cells were returned to normal growth temperature (28 degrees C) or MG132 was removed from the medium, the trehalose content and resistance to oxygen radicals decreased rapidly. Furthermore, a mutant unable to synthesize trehalose was much more sensitive to killing by oxygen radicals than wild-type cells. Providing trehalose exogenously enhanced the resistance of mutant cells to H(2)O(2). Exposure of cells to H(2)O(2) caused oxidative damage to amino acids in cellular proteins, and trehalose accumulation was found to reduce such damage. After even brief exposure to H(2)O(2), the trehalose-deficient mutant exhibited a much higher content of oxidatively damaged proteins than wild-type cells. Trehalose accumulation decreased the initial appearance of damaged proteins, presumably by acting as a free radical scavenger. Therefore, trehalose accumulation in stressed cells plays a major role in protecting cellular constituents from oxidative damage.
Highlights
Dation in cell membranes [4]
Cell Resistance to Oxygen Radicals Correlates with Trehalose Content—In yeast, trehalose is barely detectable during logarithmic phase but accumulates to very high levels during heat shock or under other stressful conditions [15,16,17]
To investigate whether this accumulation of trehalose may enhance the resistance of the cells to oxidants, exponentially growing wildtype yeast cells were exposed to a mild heat shock at 38 °C
Summary
Saccharomyces cerevisiae Strains—The ise strain JN284: MAT␣ his leu ura ise1) was provided kindly by J. Assay of Cell Resistance to H2O2—Cells were grown at 25 or 28 °C until mid-log phase and either subjected to a mild heat shock (35 or 38 °C) or exposed at 28 °C to 50 M proteasome inhibitor MG132 (in 0.1% Me2SO) (kindly provided by Proscript, Inc.) for varying periods to enhance trehalose accumulation. After these pre-treatments, cells were incubated with 2 mM H2O2 and 1 mM FeCl3 at 28 °C for the indicated times. Coomassie Blue staining was used to ensure that equal amounts of proteins were loaded onto the gel
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