酿酒酵母蛋白激酶Sch9的PDK1位点调控C末端磷酸化状态

PDK1 site of Saccharomyces cerevisiae protein kinase Sch9 regulates C terminal phosphorylation conditions

利用酿酒酵母蛋白激酶Sch9(哺乳动物p70S6k1的同源物)PDK1和PDK2位点点突变的两种突变体,分别进行生长、寿命表型检测及免疫印迹分析实验,发现PDK1位点的磷酸化水平对于Sch9活性起着主导性作用,并且PDK1位点发生去磷酸化会促进C末端高度磷酸化,而PDK1发生磷酸化会抑制C末端的磷酸化.由此说明Sch9上PDK1和PDK2位点是否发生磷酸化除了受到各自上游激酶的调节外,两者之间还存在着一种负调控机制.

The phosphorylation levels of two main phosphorylation sites on Sch9,namely PDK1 site and PDK2 site,are regulated by protein kinases of their upstream and the alterant phosphorylation also changes Sch9 activity.In this way,Sch9 seems like a signal hinge to transfer biological signals.Using two mutants of point mutation of PDK1 and PDK2sites,growth assay,chronological lifespan detection and western blotting were done.The phosphorylation at the PDK1 site is indispensable for Sch9 activity.In addition,dephosphorylation at PDK1 site can induce prominent phosphorylation at C terminal.On the contrary,phosphorylation of the PDK1 site depresses phosphorylation at C terminal.Thus,phosphorylation conditions of PDK1 and PDK2site on Sch9 are not only regulated by theirself-upstream,but also influenced by a negative control mechanism existing in their interaction.