Evangelista C C, Rodriguez Torres A M, Limbach M P, Zitomer R S
Department of Biological Sciences, State University of New York, Albany 12222, USA.
Genetics. 1996 Apr;142(4):1083-93. doi: 10.1093/genetics/142.4.1083.
Yeast respond to a variety of stresses through a global stress response that is mediated by a number of signal transduction pathways and the cis-acting STRE DNA sequence. The CYC7 gene, encoding iso-2-cytochrome c, has been demonstrated to respond to heat shock, glucose starvation, approach-to-stationary phase, and, as we demonstrate here, to osmotic stress. This response was delayed in a the hog1-delta 1 strain implicating the Hog1 mitogen-activated protein kinase cascade, a known component of the global stress response. Deletion analysis of the CYC7 regulatory region suggested that three STRE elements were each capable of inducing the stress response. Mutations in the ROX3 gene prevented CYC7 RNA accumulation during heat shock and osmotic stress. ROX3 RNA levels were shown to be induced by stress through a novel regulatory element. A selection for high-copy suppressors of a ROX3 temperature-sensitive allele resulted in the isolation of RTS1, encoding a protein with homology to the B' regulatory subunit of protein phosphatase 2A0. Deletion of RTS1 caused temperature and osmotic sensitivity and increased accumulation of CYC7 RNA under all conditions. Over-expression of this gene caused increased CYC7 RNA accumulation in rox3 mutants but not in wild-type cells.
酵母通过由多种信号转导途径和顺式作用的STRE DNA序列介导的全局应激反应来应对各种应激。编码同工型2-细胞色素c的CYC7基因已被证明对热休克、葡萄糖饥饿、接近稳定期有反应，并且正如我们在此所证明的，对渗透应激也有反应。在hog1-delta 1菌株中，这种反应被延迟，这暗示了Hog1丝裂原活化蛋白激酶级联反应，这是全局应激反应的一个已知组成部分。对CYC7调控区的缺失分析表明，三个STRE元件各自都能够诱导应激反应。ROX3基因的突变阻止了热休克和渗透应激期间CYC7 RNA的积累。ROX3 RNA水平通过一个新的调控元件被应激诱导。对ROX3温度敏感等位基因的高拷贝抑制子进行筛选，结果分离出了RTS1，它编码一种与蛋白磷酸酶2A0的B'调节亚基具有同源性的蛋白质。RTS1的缺失导致温度和渗透敏感性，并在所有条件下增加CYC7 RNA的积累。该基因的过表达导致rox3突变体中CYC7 RNA积累增加，但在野生型细胞中没有增加。
