ArsA是大腸桿菌抗砷系統中的催化次單元，可利用ATP的能量將進入細胞的砷化物及銻化物排出而產生抗性。YDL100cp是釀酒酵母中的ArsA同源蛋白，先前研究結果顯示YDL100cp與釀酒酵母的抗砷性機制無直接關係，但缺乏YDL100c基因的釀酒酵母對鋅離子具敏感性，且此敏感性在37oC時比在30oC時更為顯著。本研究為探討YDL100c基因對鋅離子敏感性表現的影響，將野生型菌株（WT）及YDL100c基因缺乏的突變株（KO）分別於30oC和37oC培養6小時觀察添加鋅離子的影響，並針對菌株的trehalose累積、細胞內分子氧化程度與GSH含量進行分析。初步結果顯示，生長於37oC時，KO的生長比WT落後，且其細胞內氧化程度較WT增加。添加鋅離子後，只有生長於37oC時，KO的細胞內氧化程度比WT增加，GSH含量較少於WT，而進一步分析抗氧化系統與相關基因的功能時，顯示在37oC成長的WT和KO，其SOD1的表現並無顯著差異，其CTT1的表現量則是KO低於WT，添加鋅離子後，對WT及KO的catalase活性均有促進作用，但KO的活性仍低於WT，而KO的CTT1的表現量在37oC添加鋅離子後並無太大差異，顯示溫度效應大於金屬離子效應。綜合以上結果YDL100c基因的缺失造成KO在37oC時的一般壓力反應的活化有缺失，使得GSH含量下降及trehalose的累積，造成細胞內氧化程度增加，而間接造成KO在37oC生長時對鋅離子的敏感性。

ArsA is the catalytic component of an arsenite extrusion pump in E. coli that confers arsenite and antimonite resistance. YDL100cp is the ArsA homologous protein found in S. cerevisiae. Previous studies show that YDL100c gene is not directly related to arsenical resistance mechanism in S. cerevisiae but the YDL100c disrupted strain (KO) showed sensitivity to Zn2+ at 30oC and more pronounced sensitivity at 37oC. To study the role of YDL100c on Zn2+ sensitivity, wild type strain (WT) and KO were grown at 30oC and 37oC for 6 hr after adding Zn2+. Both strains were assayed for trehalose accumulation, intracellular oxidation level and GSH content. The results demonstrate that KO had a decreased growth and increased intracellular oxidation at 37oC when compared to WT. Addition of Zn2+ did not increase the intracellular oxidation in WT and KO grown at 30oC but to a greater extent in KO compared to WT grown at 37oC. Further assess the function of antioxidant genes shows that there is no significant difference in SOD1 expression between KO and WT grown at 37oC but CTT1 expression is low in KO. There is an increase in catalase activity for both WT and KO by adding Zn2+ at 30oC or 37oC, but the level of catalase activity to KO is still lower than that of WT.In conclusion, a defect of YDL100c results in a defect in the activation of general stress response at 37oC. Consequently, the cause of the increased level of intracellular oxidation of KO in the presence of Zn2+ grown at 37oC is most likely related to the decrease in cellular GSH content and trehalose accumulation in KO compared to that of WT. Therefore, the pronounced sensitivity to Zn2+ at 37oC is mainly due to a defect in general stress response in KO when grown at 37oC.

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