Departament de Bioquímica i Biologia Molecular, Facultat de Ciències Biològiques, Universitat de València, Dr, Moliner, 50, E-46100, Burjassot, Valencia, Spain.
BMC Mol Biol. 2012 Jun 21;13:19. doi: 10.1186/1471-2199-13-19.
While growing in natural environments yeasts can be affected by osmotic stress provoked by high glucose concentrations. The response to this adverse condition requires the HOG pathway and involves transcriptional and posttranscriptional mechanisms initiated by the phosphorylation of this protein, its translocation to the nucleus and activation of transcription factors. One of the genes induced to respond to this injury is YHR087W. It encodes for a protein structurally similar to the N-terminal region of human SBDS whose expression is also induced under other forms of stress and whose deletion determines growth defects at high glucose concentrations.
In this work we show that YHR087W expression is regulated by several transcription factors depending on the particular stress condition, and Hot1p is particularly relevant for the induction at high glucose concentrations. In this situation, Hot1p, together to Sko1p, binds to YHR087W promoter in a Hog1p-dependent manner. Several evidences obtained indicate Yhr087wp's role in translation. Firstly, and according to TAP purification experiments, it interacts with proteins involved in translation initiation. Besides, its deletion mutant shows growth defects in the presence of translation inhibitors and displays a slightly slower translation recovery after applying high glucose stress than the wild type strain. Analyses of the association of mRNAs to polysome fractions reveals a lower translation in the mutant strain of the mRNAs corresponding to genes GPD1, HSP78 and HSP104.
The data demonstrates that expression of Yhr087wp under high glucose concentration is controlled by Hot1p and Sko1p transcription factors, which bind to its promoter. Yhr087wp has a role in translation, maybe in the control of the synthesis of several stress response proteins, which could explain the lower levels of some of these proteins found in previous proteomic analyses and the growth defects of the deletion strain.
在自然环境中生长时，酵母会受到高葡萄糖浓度引起的渗透压胁迫的影响。对这种不利条件的反应需要 HOG 途径，并涉及由该蛋白磷酸化引发的转录和转录后机制，其易位到核并激活转录因子。响应这种损伤而诱导的基因之一是 YHR087W。它编码的蛋白质结构上类似于人类 SBDS 的 N 端区域，其表达也在其他形式的应激下诱导，并且其缺失决定了在高葡萄糖浓度下的生长缺陷。
在这项工作中，我们表明 YHR087W 的表达受几种转录因子的调节，这取决于特定的应激条件，而 Hot1p 在高葡萄糖浓度下的诱导中尤为重要。在这种情况下，Hot1p 与 Sko1p 一起以 Hog1p 依赖性方式结合到 YHR087W 启动子上。获得的几项证据表明 Yhr087wp 在翻译中起作用。首先，根据 TAP 纯化实验，它与参与翻译起始的蛋白质相互作用。此外，其缺失突变体在存在翻译抑制剂时显示生长缺陷，并且在施加高葡萄糖应激后比野生型菌株的翻译恢复稍慢。对 mRNAs 与多核糖体分数的关联分析表明，突变菌株中对应于 GPD1、HSP78 和 HSP104 基因的 mRNAs 的翻译水平较低。
数据表明，Yhr087wp 在高葡萄糖浓度下的表达受 Hot1p 和 Sko1p 转录因子的控制，它们结合到其启动子上。Yhr087wp 在翻译中起作用，可能在控制几种应激反应蛋白的合成中起作用，这可以解释在以前的蛋白质组学分析中发现的这些蛋白中的一些蛋白水平较低和缺失菌株的生长缺陷。
