Stress and developmental regulation of the yeast C-type cyclin Ume3p (Srb11p/Ssn8p)
Stress and developmental regulation of the yeast C-type cyclin Ume3p (Srb11p/Ssn8p)
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DOI：
10.1093/emboj/16.15.4665
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发表时间：
1997-08-01
期刊：
影响因子：
11.4
通讯作者：
Strich, R
中科院分区：
文献类型：
--
作者：
Cooper, KF;Mallory, MJ;Strich, R
在酿酒酵母的有丝分裂细胞分裂过程中，ume3-1等位基因突变导致了数个减数分裂基因（如SPO11、SPO13）的异常表达。在这里，我们报道了UME3也是HSP70家族成员SSA1完全抑制所必需的。UME3编码一种非必需c型周期蛋白（Ume3p），其水平在有丝分裂细胞周期中不变化，然而，Ume3p在减数分裂或培养物受到热休克时被破坏。抗降解的Ume3p突变体导致减数分裂期间SPO13 mRNA水平降低2倍，表明该细胞周期蛋白的下调对正常减数分裂基因表达很重要。突变分析鉴定了介导Ume3p降解的两个区域（PEST-rich和RXXL）。第三个破坏信号位于高度保守的周期蛋白盒内，该区域介导周期蛋白-周期蛋白依赖性激酶（Cdk）的相互作用。然而，由Ume3p （Ume5p）激活的Cdk并不是快速破坏该周期蛋白所必需的。最后，在泛素依赖性蛋白水解缺陷突变体中，Ume3p的破坏不受影响。这些结果支持了一个模型，即当暴露于热休克或产孢条件下时，Ume3p会被破坏，以允许细胞对这些环境线索做出正确反应所需的基因表达。
The ume3-1 allele was identified as a mutation that allowed the aberrant expression of several meiotic genes (e.g. SPO11, SPO13) during mitotic cell division in Saccharomyces cerevisiae. Here we report that UME3 is also required for the full repression of the HSP70 family member SSA1. UME3 encodes a nan-essential C-type cyclin (Ume3p) whose levels do not vary through the mitotic cell cycle, However, Ume3p is destroyed during meiosis or when cultures are subjected to heat shock. Ume3p mutants resistant to degradation resulted in a 2-fold reduction in SPO13 mRNA levels during meiosis, indicating that the down-regulation of this cyclin is important for normal meiotic gene expression, Mutational analysis identified two regions (PEST-rich and RXXL) that mediate Ume3p degradation. A third destruction signal lies within the highly conserved cyclin box, a region that mediates cyclin-cyclin-dependent kinase (Cdk) interactions, However, the Cdk activated by Ume3p (Ume5p) is not required for the rapid destruction of this cyclin. Finally, Ume3p destruction was not affected in mutants defective for ubiquitin-dependent proteolysis. These results support a model in which Ume3p, when exposed to heat shock or sporulation conditions, is targeted for destruction to allow the expression of genes necessary for the cell to respond correctly to these environmental cues.