Elliott B, Haltiwanger R S, Futcher B
Cold Spring Harbor Laboratory, New York 11724, USA.
Genetics. 1996 Nov;144(3):923-33. doi: 10.1093/genetics/144.3.923.
We isolated a mutant strain unable to acquire heat shock resistance in stationary phase. Two mutations contributed to this phenotype. One mutation was at the TPS2 locus, which encodes trehalose-6-phosphate phosphatase. The mutant fails to make trehalose and accumulates trehalose-6-phosphate. The other mutation was at the HSP104 locus. Gene disruptions showed that tps2 and hsp104 null mutants each produced moderate heat shock sensitivity in stationary phase cells. The two mutations were synergistic and the double mutant had little or no stationary phase-induced heat shock resistance. The same effect was seen in the tps1 (trehalose-6-phosphate synthase) hsp104 double mutant, suggesting that the extreme heat shock sensitivity was due mainly to a lack of trehalose rather than to the presence of trehalose-6-phosphate. However, accumulation of trehalose-6-phosphate did cause some phenotypes in the tps2 mutant, such as temperature sensitivity for growth. Finally, we isolated a high copy number suppressor of the temperature sensitivity of tps2, which we call PMU1, which reduced the levels of trehalose-6-phosphate in tps2 mutants. The encoded protein has a region homologous to the active site of phosphomutases.
我们分离出了一株在稳定期无法获得热休克抗性的突变菌株。有两个突变导致了这种表型。一个突变发生在TPS2位点，该位点编码海藻糖-6-磷酸磷酸酶。该突变体无法合成海藻糖并积累了海藻糖-6-磷酸。另一个突变发生在HSP104位点。基因破坏实验表明，tps2和hsp104基因敲除突变体在稳定期细胞中各自产生了中等程度的热休克敏感性。这两个突变具有协同作用，双突变体几乎没有或完全没有稳定期诱导的热休克抗性。在tps1（海藻糖-6-磷酸合酶）hsp104双突变体中也观察到了相同的效应，这表明极端的热休克敏感性主要是由于缺乏海藻糖而不是由于存在海藻糖-6-磷酸。然而，海藻糖-6-磷酸的积累确实在tps2突变体中导致了一些表型，例如生长的温度敏感性。最后，我们分离出了一个tps2温度敏感性的高拷贝数抑制子，我们将其命名为PMU1，它降低了tps2突变体中海藻糖-6-磷酸的水平。编码的蛋白质有一个与磷酸变位酶活性位点同源的区域。
