Substrate-Induced Changes in the Dynamics of Rhodopsin Kinase (G Protein-Coupled Receptor Kinase 1)
Substrate-Induced Changes in the Dynamics of Rhodopsin Kinase (G Protein-Coupled Receptor Kinase 1)
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DOI：
10.1021/bi300295y
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发表时间：
2012-04-24
期刊：
影响因子：
2.9
通讯作者：
Palczewski, Krzysztof
中科院分区：
文献类型：
--
作者：
Orban, Tivadar;Huang, Chih-chin;Palczewski, Krzysztof
G 蛋白偶联受体 (GPCR) 激酶 (GRK) 通过磷酸化促进激活的 GPCR 脱敏，从而促进与抑制蛋白的相互作用，从而阻止 GPCR 与异三聚体 G 蛋白的相互作用。目前提出的 GRK1 激活模型涉及激活的视紫红质 (Rho*) 与 GRK1 N 末端区域的结合。也许同时，这个 N 末端区域也稳定了激酶结构域的封闭、活性构象。为了进一步探讨该模型，我们绘制了 GRK1 在与其两种底物三磷酸腺苷 (Mg2+.ATP) 和 Rho* 结合时主链灵活性的变化。我们发现，当 Mg2+.ATP 或 Rho* 存在时，GRK1 的构象灵活性会降低，其中 Mg2+.ATP 的影响最大。在缺少 N 末端区域的 GRK1 截短形式 (Delta N-GRK1) 中，直接与 ATP 相互作用的肽不会通过添加 Mg2+.ATP 得到显着稳定，并且激酶结构域大叶与 G 蛋白信号同源结构域调节器之间的界面动态更大。在 Mg2+.ATP 存在的情况下，Rho* 与 Rho 对 GRK1 动力学的影响可以忽略不计。
G protein-coupled receptor (GPCR) kinases (GRKs) instigate the desensitization of activated GPCRs via phosphorylation that promotes interaction with arrestins, thereby preventing the interaction of GPCRs with heterotrimeric G proteins. A current proposed model of GRK1 activation involves the binding of activated rhodopsin (Rho*) to the N-terminal region of GRK1. Perhaps concomitantly, this N-terminal region also stabilizes a closed, active conformation of the kinase domain. To further probe this model, we mapped changes in the backbone flexibility of GRK1 as it binds to its two substrates, adenosine triphosphate (Mg2+.ATP) and Rho*. We found that the conformational flexibility of GRK1 was reduced in the presence of either Mg2+.ATP or Rho*, with Mg2+.ATP having the greatest effect. In a truncated form of GRK1 lacking the N-terminal region (Delta N-GRK1), peptides that directly interact with ATP were not as dramatically stabilized by adding Mg2+.ATP, and dynamics were greater in the interface between the large lobe of the kinase domain and the regulator of the G protein signaling homology domain. In the presence of Mg2+.ATP, the influence of Rho* versus Rho on GRK1 dynamics was negligible.