Mechanistic link between PKR dimerization, autophosphorylation, and elF2α substrate recognition
Mechanistic link between PKR dimerization, autophosphorylation, and elF2α substrate recognition
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DOI：
10.1016/j.cell.2005.06.041
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发表时间：
2005-09-23
期刊：
影响因子：
64.5
通讯作者：
Dever, TE
中科院分区：
文献类型：
--
作者：
Dey, M;Cao, C;Dever, TE
抗病毒蛋白激酶PKR通过磷酸化Ser51上的翻译起始因子eIF2 α来抑制蛋白质合成。双链RNA与PKR调控结构域的结合促进二聚化、自磷酸化和激酶的功能活化。在此，我们确定了激活PKR的突变，在其调节结构域的情况下，并映射到最近确定的激酶催化结构域上的二聚化表面的突变。该表面上的其他残基的突变阻断PKR自磷酸化和eIF2 α磷酸化，而突变催化结构域活化区段内的自磷酸化位点Thr446损害eIF2 α磷酸化和病毒假底物结合。在eIF2 α激酶家族中优先保守的催化结构域残基的突变分析确定螺旋α G对于eIF2 α的特异性识别至关重要。我们提出了一个有序的PKR激活机制，其中催化结构域的climerization触发Thr446自磷酸化和特定的eIF2 α底物识别。
The antiviral protein kinase PKR inhibits protein synthesis by phosphorylating the translation initiation factor eIF2 alpha on Ser51. Binding of double-stranded RNA to the regulatory domains of PKR promotes dimerization, autophosphorylation, and the functional activation of the kinase. Herein, we identify mutations that activate PKR in the absence of its regulatory domains and map the mutations to a recently identified dimerization surface on the kinase catalytic domain. Mutations of other residues on this surface block PKR autophosphorylation and eIF2 alpha phosphorylation, while mutating Thr446, an autophosphorylation site within the catalytic-domain activation segment, impairs eIF2 alpha phosphorylation and viral pseudosubstrate binding. Mutational analysis of catalytic-domain residues preferentially conserved in the eIF2 alpha kinase family identifies helix alpha G as critical for the specific recognition of eIF2 alpha. We propose an ordered mechanism of PKR activation in which catalytic-domain climerization triggers Thr446 autophosphorylation and specific eIF2 alpha substrate recognition.