A dimeric kinase assembly underlying autophosphorylation in the p21 activated kinases
A dimeric kinase assembly underlying autophosphorylation in the p21 activated kinases
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DOI：
10.1016/j.jmb.2006.06.017
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发表时间：
2006-08-11
影响因子：
5.6
通讯作者：
Kuriyan, John
中科院分区：
文献类型：
--
作者：
Pirruccello, Michelle;Sondermann, Holger;Kuriyan, John
p21活化激酶（PAKs）是丝氨酸/苏氨酸激酶，参与多种细胞功能，包括细胞骨架运动、细胞凋亡和细胞周期调节。PAKs通过一个n端调控结构域阻断激酶结构域的活性位点而失活。gtp结合形式的Cdc42和Rac结合到调节结构域并取代它，从而允许激酶结构域磷酸化并最大限度地激活。激活过程中的一个关键步骤是一个PAK激酶结构域的激活环被另一个激活环磷酸化，但对使这种磷酸化特异性的潜在识别事件知之甚少。我们发现PAK2的磷酸化激酶结构域在溶液中二聚化，并且这种结合可以通过添加底物肽来阻止。我们已经在先前确定的活化PAK1的晶体结构中发现了晶体学二聚体，其中两个激酶结构域面对面排列，并通过激酶结构域大叶上的表面相互作用，该表面在释放自抑制结构域时暴露。晶体二聚体暗示了介导反式自磷酸化的接合。预测二聚化界面的突变阻断了二聚化并降低了自磷酸化的速率，支持了该界面在PAK激活中的作用。(c) 2006 Elsevier Ltd.版权所有。
The p21-activated kinases (PAKs) are serine/threonine kinases that are involved in a wide variety of cellular functions including cytoskeletal motility, apoptosis, and cell cycle regulation. PAKs are inactivated by blockage of the active site of the kinase domain by an N-terminal regulatory domain. GTP-bound forms of Cdc42 and Rac bind to the regulatory domain and displace it, thereby allowing phosphorylation of the kinase domain and maximal activation. A key step in the activation process is the phosphorylation of the activation loop of one PAK kinase domain by another, but little is known about the underlying recognition events that make this phosphorylation specific. We show that the phosphorylated kinase domain of PAK2 dimerizes in solution and that this association is prevented by addition of a substrate peptide. We have identified a crystallographic dimer in a previously determined crystal structure of activated PAK1 in which two kinase domains are arranged face to face and interact through a surface on the large lobe of the kinase domain that is exposed upon release of the autoinhibitory domain. The crystallographic dimer is suggestive of an engagement that mediates trans-autophosphorylation. Mutations at the predicted dimerization interface block dimerization and reduce the rate of autophosphorylation, supporting the role of this interface in PAK activation. (c) 2006 Elsevier Ltd. All rights reserved.