Screening for modulators of spermine tolerance identifies Sky1, the SR protein kinase of Saccharomyces cerevisiae, as a regulator of polyamine transport and ion homeostasis
Screening for modulators of spermine tolerance identifies Sky1, the SR protein kinase of Saccharomyces cerevisiae, as a regulator of polyamine transport and ion homeostasis
复制标题
DOI：
10.1128/mcb.21.1.175-184.2001
复制
发表时间：
2001-01-01
影响因子：
5.3
通讯作者：
Kahana, C
中科院分区：
文献类型：
--
作者：
Erez, O;Kahana, C
尽管大多数细胞能够运输多胺，但在真核生物中调节多胺运输的机制在很大程度上仍不清楚。通过对能够恢复酿酒酵母耐精胺突变株精胺敏感性的克隆的遗传筛选，我们证明了新近发现的SR蛋白激酶Sky1p是多胺运输的关键调节因子。缺失Sky1基因的酵母细胞对毒性水平的精胺产生了耐受性，而野生型细胞中Sky1p的过表达增加了它们对精胺的敏感性。野生型Sky1p的表达，而不是催化失活突变体的表达，恢复了对精胺的敏感性。Sky1的中断导致精胺、亚精胺和腐胺的摄取显著减少。除了精胺耐受性外，Sky1 Delta细胞对锂离子和钠离子的耐受性增加，但对渗透性休克的敏感性有所增加。观察到的耐卤性表明多胺运输和无机离子之间潜在的调节相互作用，就像最近描述的多胺运输调节因子Ptk2p的情况一样。我们证明这两种蛋白在两条不同的信号通路中起作用。虽然Sky1的缺失或过表达对Pma1p活性没有显著影响，但过表达的Sky1p、Ptk1p和Ptk2p增加对LiCl敏感性的能力取决于PPZ1的完整性，而不是ENA1的完整性。
Although most cells are capable of transporting polyamines, the mechanism that regulates polyamine transport in eukaryotes is still largely unknown. Using a genetic screen for clones capable of restoring spermine sensitivity to spermine-tolerant mutants of Saccharomyces cerevisiae, we have demonstrated that Sky1p, a recently identified SR protein kinase, is a key regulator of polyamine transport. Yeast cells deleted for SKY1 developed tolerance to toxic levels of spermine, while overexpression of Sky1p in wild-type cells increased their sensitivity to spermine. Expression of the wild-type Sky1p but not of a catalytically inactive mutant restored sensitivity to spermine. SKY1 disruption results in dramatically reduced uptake of spermine, spermidine, and putrescine. In addition to spermine tolerance, sky1 Delta cells exhibit increased tolerance to lithium and sodium ions but somewhat increased sensitivity to osmotic shock. The observed halotolerance suggests potential regulatory interaction between the transport of polyamines and inorganic ions, as suggested in the case of the Ptk2p, a recently described regulator of polyamine transport. We demonstrate that these two kinases act in two different signaling pathways. While deletion or overexpression of SKY1 did not significantly affect Pma1p activity, the ability of overexpressed Sky1p, Ptk1p, and Ptk2p to increase sensitivity to LiCl depends on the integrity of PPZ1 but not of ENA1.