The mechanism of dephosphorylation of extracellular signal-regulated kinase 2 by mitogen-activated protein kinase phosphatase 3
The mechanism of dephosphorylation of extracellular signal-regulated kinase 2 by mitogen-activated protein kinase phosphatase 3
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DOI：
10.1074/jbc.m103369200
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发表时间：
2001-08-24
影响因子：
4.8
通讯作者：
Zhang, ZY
中科院分区：
文献类型：
--
作者：
Zhao, Y;Zhang, ZY
丝裂原活化蛋白（MAP）激酶磷酸酶-3（MKP 3）是一种双特异性磷酸酶，可特异性灭活MAP激酶的一个亚家族，即细胞外信号调节激酶（ERK）。MAP激酶的失活通过TXY激酶活化基序中的Thr（P）和Tyr（P）的去磷酸化而发生。为了深入了解MKP 3对ERK 2的失活机制，我们对磷酸化ERK 2的MKP 3催化的去磷酸化进行了分析。我们发现MKP 3对ERK 2/pTpY的去磷酸化涉及一种有序的分布机制，其中MKP 3结合双磷酸化的ERK 2/pTpY，首先使Tyr（P）去磷酸化，解离并释放单磷酸化的ERK 2/pT，然后通过第二个MKP 3进行去磷酸化，产生完全去磷酸化的ERK 2。二磷酸化ERK 2是MKP 3的高度特异性底物，k（cat）/K-m为3.8 x 10（6）m（-1）s（-1），比小分子芳基磷酸酯和包含pTEpY基序的ERK 2衍生磷酸肽高6个数量级以上。MKP 3显示的这种惊人的高底物特异性可能是MKP 3和ERK 2的N-末端结构域之间的高亲和力结合相互作用和MKP 3 C-末端磷酸酶结构域的特异性ERK 2诱导的变构活化的组合。
The mitogen-activated protein (MAP) kinase phosphatase-3 (MKP3) is a dual specificity phosphatase that specifically inactivates one subfamily of MAP kinases, the extracellular signal-regulated kinases (ERKs). Inactivation of MAP kinases occurs by dephosphorylation of Thr(P) and Tyr(P) in the TXY kinase activation motif. To gain insight into the mechanism of ERK2 inactivation by MKP3, we have carried out an analysis of the MKP3-catalyzed dephosphorylation of the phosphorylated ERK2. We find that ERK2/pTpY dephosphorylation by MKP3 involves an ordered, distributive mechanism in which MKP3 binds the bisphosphorylated ERK2/pTpY, dephosphorylates Tyr(P) first, dissociates and releases the monophosphorylated ERK2/pT, which is then subjected to dephosphorylation by a second MKP3, yielding the fully dephosphorylated ERK2. The bisphosphorylated ERK2 is a highly specific substrate for MKP3 with a k(cat)/K-m of 3.8 x 10(6) m(-1) s(-1), which is more than 6 orders of magnitude higher than that for small molecule aryl phosphates and an ERK2-derived phosphopeptide encompassing the pTEpY motif. This strikingly high substrate specificity displayed by MKP3 may result from a combination of high affinity binding interactions between the N-terminal domain of MKP3 and ERK2 and specific ERK2-induced allosteric activation of the MKP3 C-terminal phosphatase domain.