The gatekeeper residue controls autoactivation of ERK2 via a pathway of intramolecular connectivity
The gatekeeper residue controls autoactivation of ERK2 via a pathway of intramolecular connectivity
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DOI：
10.1073/pnas.0608849103
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发表时间：
2006-11-28
影响因子：
11.1
通讯作者：
Ahn, Natalie G.
中科院分区：
文献类型：
--
作者：
Emrick, Michelle A.;Lee, Thomas;Ahn, Natalie G.
蛋白激酶的研究已经确定了一个“看门人”残基，它赋予结合核苷酸和小分子抑制剂的选择性。我们报告说，在MAP激酶ERK 2，在看门人残基的突变意外地导致自激活，由于增强的自磷酸化的调节酪氨酸和苏氨酸位点内的激活唇，控制激酶活性。这是通过分子内机制发生的，表明看门人残基间接限制了激活唇的灵活性，排除了磷酸受体残基对催化碱基的访问。与守门位点相互作用以在N-末端结构域中形成疏水簇的其他残基在突变时也引起自激活。该簇内的突变体的氢交换研究揭示了保守的DFG基序的扰动，预测从疏水簇到活化唇的侧链连接的路线。沿着沿着这条路线的残基突变支持这一模型，解释了关于看门人残基身份的信息如何可以被传输到激活唇。因此，一个N-末端疏水簇，包括看门人形成了一个新的结构单元，其功能是保持细胞信号激活前的ERK 2的“关闭”状态。
Studies of protein kinases have identified a "gatekeeper" residue, which confers selectivity for binding nucleotides and small-molecule inhibitors. We report that, in the MAP kinase ERK2, mutations at the gatekeeper residue unexpectedly lead to autoactivation due to enhanced autophosphorylation of regulatory Tyr and Thr sites within the activation lip that control kinase activity. This occurs through an intramolecular mechanism, indicating that the gatekeeper residue indirectly constrains flexibility at the activation lip, precluding access of the phosphoacceptor residues to the catalytic base. Other residues that interact with the gatekeeper site to form a hydrophobic cluster in the N-terminal domain also cause autoactivation when mutated. Hydrogen-exchange studies of a mutant within this cluster reveal perturbations in the conserved DFG motif, predicting a route for side chain connectivity from the hydrophobic cluster to the activation lip. Mutations of residues along this route support this model, explaining how information about the gatekeeper residue identity can be transmitted to the activation lip. Thus, an N-terminal hydrophobic cluster that includes the gatekeeper forms a novel structural unit, which functions to maintain the "off" state of ERK2 before cell signal activation.