YDL100Cp is the ArsA homologue protein found in S. cerevisiae. In bacteria, ArsA protein is involved in As3+detoxification but the function of YDL100Cp is still unknown. Previous studies show that deletion of YDL100C in S. cerevisiae was not lethal and had no effect on As3+ sensitivity or growth at 30¢J. However, when grown at 40¢J, growth of YDL100C disrupted strain (JSY1) was inhibited. To study the role of YDL100C in response to lethal heat shock, wild type (W303-1B) and JSY1 cells were exposed to 50¢J for 15 min. The survival rate of JSY1 cells was half of W303-1B cells and the difference in survival rate was complemented by introduction of plasmid carrying YDL100C. It suggests that YDL100Cp plays a role in acquisition of thermotolerance to lethal heat shock. It is believed that there are two factors involved in heat-induced cell death: the heat damage and the oxidative damage. Determinations of heat-damage related defense system in S. cerevisiae, including trehalose (a thermoprotectant) content, Hsp70 expression and Hsp104 expression, demonstrate that heat damage should not be the major cause of JSY1 cell death during heat shock. For the oxidative damage, the measurement of in vivo reactive oxygen species reveal the lower protein damage caused by reactive oxygen species (ROS) in JSY-1 after 50¢J 15 min heat shock, this might reflect the difference in viability of three strains under lethal heat shock. And with the intra cellular content of glutathione, it revels that the YDL100C deficient caused cell got more serious oxidative damage under 50¢J heat shock. But the observation of thermotolerance related ROS scavenger system (including the catalase, and superoxide dismutase) expression with reverse transcription polymerase chain reaction suggested that YDL100C deficient had no effect on triggering these system. As the result, it is suggested that the function of YDL100Cp in S. cerevisiae might be an oxidative damage repair system, such as the glutathione peroxidase. It might react with the oxidative damage substance and function as a deoxidizer.

YDL100cp is the ArsA homologous protein found in Saccharomyces cerevisiae. Previous studies show that deletion of YDL100c was not lethal but unable to grow at 40¢XC. To study the role of YDL100c in response to lethal heat shock, the wild type strain (WT) and YDL100c disrupted strain (KO) were exposed to 50¢XC for 30 min. The growth and survival rate of KO cells at 30¢XC after heat-shock was lower than that of WT cells, and the difference was complementated by introducing the plasmid carrying YDL100c. The oxidative stress has been shown to be involved in the heat-induced cell death in S. cerevisiae. Therefore, the intracellular molecular oxidation level, expression of antioxidant genes, trehalose accumulation, and glutathione (GSH) content were further examined. The intracellular molecular oxidation was increased in KO compared to WT when exposed to 50¢XC, suggesting heat-shock-induced cell death is related to oxidation of intracellular components. The results also demonstrated that both WT and KO had a decreased GSH content and trehalose accumulation after heat-shock, indicating that GSH and trehalose are not directly involved in the slow growth of KO after heat-shock. However, CTT1 expression is decreased in KO compared to WT when exposed to 50¢XC, suggesting that decreased CTT1 expression resulted in the increased intracellular oxidation and YDL100c is likely involved in the activation of CTT1 expression.