Structurally unique yeast and mammalian serine-arginine protein kinases catalyze evolutionarily conserved phosphorylation reactions
Structurally unique yeast and mammalian serine-arginine protein kinases catalyze evolutionarily conserved phosphorylation reactions
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DOI：
10.1074/jbc.m611305200
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发表时间：
2007-08-10
影响因子：
4.8
通讯作者：
Ghosh, Gourisankar
中科院分区：
文献类型：
--
作者：
Lukasiewicz, Randall;Velazquez-Dones, Adolfo;Ghosh, Gourisankar
哺乳动物的丝氨酸-精氨酸(SR)蛋白ASF/SF2在C端含有多个连续的RS二肽，与其中的12个类似，被SR蛋白激酶1(SRPK1)磷酸化。我们最近发现ASF/SF2中的一个对接基序与SRPK1中的一个凹槽特异地相互作用，这种相互作用是过程磷酸化所必需的。我们先前已经证明SRPK1及其酵母同源基因Sky1p通过不同的结构策略维持其活性构象。在这里，我们测试了SRPK对ASF/SF2磷酸化的机制是否在进化上是保守的。我们发现Sky1p与其异源哺乳动物底物ASF/SF2形成稳定的络合物，并与SRPK1过程地磷酸化相同的位点。我们进一步证明，Sky1p利用相同的对接槽来结合酵母SR样蛋白Gbp2p，并磷酸化存在于连续RS二肽延伸中的所有三个丝氨酸。然而，Gbp2p的磷酸化机制似乎是非过程性的。因此，SR和类SR底物的物理属性决定了磷酸化的机制，而处理磷酸化底物的能力是SR蛋白激酶所固有的。
The mammalian serine-arginine (SR) protein, ASF/SF2, contains multiple contiguous RS dipeptides at the C terminus, and similar to 12 of these serines are processively phosphorylated by the SR protein kinase 1 (SRPK1). We have recently shown that a docking motif in ASF/SF2 specifically interacts with a groove in SRPK1, and this interaction is necessary for processive phosphorylation. We previously showed that SRPK1 and its yeast ortholog Sky1p maintain their active conformations using diverse structural strategies. Here we tested if the mechanism of ASF/SF2 phosphorylation by SRPK is evolutionarily conserved. We show that Sky1p forms a stable complex with its heterologous mammalian substrate ASF/SF2 and processively phosphorylates the same sites as SRPK1. We further show that Sky1p utilizes the same docking groove to bind yeast SR-like protein Gbp2p and phosphorylates all three serines present in a contiguous RS dipeptide stretch. However, the mechanism of Gbp2p phosphorylation appears to be non-processive. Thus, there are physical attributes of SR and SR-like substrates that dictate the mechanism of phosphorylation, whereas the ability to processively phosphorylate substrates is inherent to SR protein kinases.