Mahmud Siraje Arif, Nagahisa Keisuke, Hirasawa Takashi, Yoshikawa Katsunori, Ashitani Kengo, Shimizu Hiroshi
Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Yeast. 2009 Jan;26(1):17-30. doi: 10.1002/yea.1646.
To examine the effect of trehalose accumulation on response to saline stress in Saccharomyces cerevisiae, we constructed deletion strains of all combinations of the trehalase genes ATH1, NTH1 and NTH2 and examined their growth behaviour and intracellular trehalose accumulation under non-stress and saline-stress conditions. Saline stress was induced in yeast cells by NaCl addition at the exponential growth phase. All deletion strains showed similar specific growth rates and trehalose accumulation to their parent strain under non-stress conditions. However, under the saline stress condition, one single deletion strain, nth1Delta, two double deletion strains, nth1Delta ath1Delta and nth1Delta nth2Delta, and the triple deletion strain nth1Deltanth2Delta ath1Delta, all of which carry the nth1Delta deletion, showed increased trehalose accumulation as compared to the parent and other deletion strains. In particular, our statistical analysis revealed that the triple deletion strain showed a higher growth rate under the saline stress condition than the parent strain. Moreover, some deletion strains showed further trehalose accumulation under non-stress conditions by overexpression of the TPS1 or TPS2 genes encoding the enzymes related to trehalose biosynthesis at the mid-exponential phase. Such increased trehalose accumulation prior to NaCl addition could improve the growth of these strains under saline stress. Our results indicate that high trehalose accumulation prior to NaCl addition, rather than after NaCl addition, is necessary to achieve high growth activity under stress conditions.
为了研究海藻糖积累对酿酒酵母盐胁迫反应的影响，我们构建了海藻糖酶基因ATH1、NTH1和NTH2所有组合的缺失菌株，并检测了它们在非胁迫和盐胁迫条件下的生长行为及细胞内海藻糖积累情况。在指数生长期通过添加NaCl在酵母细胞中诱导盐胁迫。在非胁迫条件下，所有缺失菌株的比生长速率和海藻糖积累与亲本菌株相似。然而，在盐胁迫条件下，一个单缺失菌株nth1Δ、两个双缺失菌株nth1Δ ath1Δ和nth1Δ nth2Δ以及三缺失菌株nth1Δnth2Δ ath1Δ（所有这些菌株都携带nth1Δ缺失）与亲本和其他缺失菌株相比，海藻糖积累增加。特别是，我们的统计分析表明，三缺失菌株在盐胁迫条件下的生长速率高于亲本菌株。此外，一些缺失菌株在指数中期通过过表达编码与海藻糖生物合成相关酶的TPS1或TPS2基因，在非胁迫条件下进一步积累海藻糖。在添加NaCl之前这种海藻糖积累的增加可以改善这些菌株在盐胁迫下的生长。我们的结果表明，在添加NaCl之前而不是之后积累高含量的海藻糖对于在胁迫条件下实现高生长活性是必要的。
