Phosphorylation-Dependent PIH1D1 Interactions Define Substrate Specificity of the R2TP Cochaperone Complex
Phosphorylation-Dependent PIH1D1 Interactions Define Substrate Specificity of the R2TP Cochaperone Complex
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DOI：
10.1016/j.celrep.2014.03.013
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发表时间：
2014-04-01
期刊：
影响因子：
8.8
通讯作者：
Boulton, Simon J.
中科院分区：
文献类型：
--
作者：
Horejsi, Zuzana;Stach, Lasse;Boulton, Simon J.
R2 TP辅助分子伴侣复合物在多亚基机器的组装中起着关键作用，包括小核仁核糖核蛋白（snoRNP），RNA聚合酶II以及mTORC 1和SMG 1激酶复合物，但底物识别的分子基础仍不清楚。在这里，我们描述了一个磷酸肽结合结构域（PIH-N）的PIH 1D 1亚基的R2 TP复合物，优先结合高度酸性磷酸化的蛋白质。PIH-N结构域/TEL 2磷酸肽复合物的共晶结构揭示了高度特异性的磷酸肽识别机制，其中PIH 1D 1中的Lys 57和64，沿着TEL 2中保守的DpSDD磷酸肽基序，对于结合是必需的和足够的。PIH 1D 1相互作用的蛋白质组学分析确定了R2 TP复合物底物，其由PIH-N结构域以序列特异性和磷酸化依赖性方式招募，提示底物识别的共同机制。我们建议，蛋白质复合物组装的R2 TP复合物的定义由一个特定的基序和识别PIH 1D 1亚基的磷酸化。
The R2TP cochaperone complex plays a critical role in the assembly of multisubunit machines, including small nucleolar ribonucleoproteins (snoRNPs), RNA polymerase II, and the mTORC1 and SMG1 kinase complexes, but the molecular basis of substrate recognition remains unclear. Here, we describe a phosphopeptide binding domain (PIH-N) in the PIH1D1 subunit of the R2TP complex that preferentially binds to highly acidic phosphorylated proteins. A cocrystal structure of a PIH-N domain/TEL2 phosphopeptide complex reveals a highly specific phosphopeptide recognition mechanism in which Lys57 and 64 in PIH1D1, along with a conserved DpSDD phosphopeptide motif within TEL2, are essential and sufficient for binding. Proteomic analysis of PIH1D1 interactors identified R2TP complex substrates that are recruited by the PIH-N domain in a sequence-specific and phosphorylation-dependent manner suggestive of a common mechanism of substrate recognition. We propose that protein complexes assembled by the R2TP complex are defined by phosphorylation of a specific motif and recognition by the PIH1D1 subunit.