1] National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China [2] University of Chinese Academy of Sciences, Beijing 100049, China [3].
1] National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China [2].
Nat Commun. 2014 Mar 28;5:3552. doi: 10.1038/ncomms4552.
Phosphatidylinositol 4-kinase IIα (PI4KIIα), a membrane-associated PI kinase, plays a central role in cell signalling and trafficking. Its kinase activity critically depends on palmitoylation of its cysteine-rich motif (-CCPCC-) and is modulated by the membrane environment. Lack of atomic structure impairs our understanding of the mechanism regulating kinase activity. Here we present the crystal structure of human PI4KIIα in ADP-bound form. The structure identifies the nucleotide-binding pocket that differs notably from that found in PI3Ks. Two structural insertions, a palmitoylation insertion and an RK-rich insertion, endow PI4KIIα with the 'integral' membrane-binding feature. Molecular dynamics simulations, biochemical and mutagenesis studies reveal that the palmitoylation insertion, containing an amphipathic helix, contributes to the PI-binding pocket and anchors PI4KIIα to the membrane, suggesting that fluctuation of the palmitoylation insertion affects PI4KIIα's activity. We conclude from our results that PI4KIIα's activity is regulated indirectly through changes in the membrane environment.
磷脂酰肌醇 4-激酶 IIα（PI4KIIα）是一种膜相关的 PI 激酶，在细胞信号转导和运输中发挥核心作用。其激酶活性的关键取决于其富含半胱氨酸的基序（-CCPCC-）的棕榈酰化，并且受膜环境的调节。缺乏原子结构会阻碍我们对调节激酶活性的机制的理解。本文呈现了人源 PI4KIIα 在 ADP 结合形式下的晶体结构。该结构确定了核苷酸结合口袋，与 PI3Ks 中发现的口袋明显不同。两个结构插入物，棕榈酰化插入物和富含 RK 的插入物，赋予 PI4KIIα“整合”的膜结合特征。分子动力学模拟、生化和突变研究表明，含有两亲性螺旋的棕榈酰化插入物有助于 PI 结合口袋，并将 PI4KIIα 锚定在膜上，这表明棕榈酰化插入物的波动会影响 PI4KIIα 的活性。我们的研究结果表明，PI4KIIα 的活性是通过膜环境的变化间接调节的。
