A novel domain in the protein kinase SOS2 mediates interaction with the protein phosphatase 2C AB12
A novel domain in the protein kinase SOS2 mediates interaction with the protein phosphatase 2C AB12
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DOI：
10.1073/pnas.2034853100
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发表时间：
2003-09-30
影响因子：
11.1
通讯作者：
Zhu, JK
中科院分区：
文献类型：
--
作者：
Ohta, M;Guo, Y;Zhu, JK
SOS2（盐过度敏感2）是拟南芥耐盐所需的丝氨酸/苏氨酸蛋白激酶。在这项研究中，我们鉴定了蛋白磷酸酶 2C ABI2（脱落酸不敏感 2）作为 SOS2 相互作用蛋白。删除分析发现了 SOS2 的一个由 37 个氨基酸残基组成的新蛋白结构域，称为蛋白磷酸酶相互作用 (PPI) 基序，它对于与 AB12 相互作用是必要且充分的。 PPI 基序在 SOS2 家族的蛋白激酶（即蛋白激酶 S、PKS）以及包括人类在内的各种生物体的 DNA 损伤修复和复制阻断检查点激酶 Chk1 中是保守的。 PPI 基序中保守氨基酸残基的突变消除了 SOS2 与 AB12 的相互作用。我们还鉴定了 AB12 中的蛋白激酶相互作用结构域，并检查了 PKS 和 ABI 磷酸酶之间的相互作用特异性。我们发现一些 PIKS 与 AB12 强烈相互作用，而另一些 PIKS 优先与 ABI1 相互作用。 SOS2 和 ABI2 之间的相互作用被 abi2-1 突变破坏，导致植物对盐休克和脱落酸不敏感的耐受性增强。我们的结果将 PPI 基序和蛋白激酶相互作用结构域确立为介导 SOS2 蛋白激酶家族和 ABI1/2 蛋白磷酸酶家族之间结合的新型蛋白相互作用结构域。
SOS2 (salt overly sensitive 2) is a serine/threonine protein kinase required for salt tolerance in Arabidopsis thaliana. In this study, we identified the protein phosphatase 2C ABI2 (abscisic acid-insensitive 2) as a SOS2-interacting protein. Deletion analysis led to the discovery of a novel protein domain of 37 amino acid residues, designated as the protein phosphatase interaction (PPI) motif, of SOS2 that is necessary and sufficient for interaction with AB12. The PPI motif is conserved in protein kinases of the SOS2 family (i.e., protein kinase S, PKS) and in the DNA damage repair and replication block checkpoint kinase, Chk1, from various organisms including humans. Mutations in the conserved amino acid residues in the PPI motif abolish the interaction of SOS2 with AB12. We also identified a protein kinase interaction domain in AB12 and examined the interaction specificity between PKS and the ABI phosphatases. We found that some PIKSs interact strongly with AB12 whereas others interact preferentially with ABI1. The interaction between SOS2 and ABI2 was disrupted by the abi2-1 mutation, which causes increased tolerance to salt shock and abscisic acid insensitivity in plants. Our results establish the PPI motif and the protein kinase interaction domain as novel protein interaction domains that mediate the binding between the SOS2 family of protein kinases and the ABI1/2 family of protein phosphatases.