Calcium/Calmodulin Dependent Protein Kinase II Bound to NMDA Receptor 2B Subunit Exhibits Increased ATP Affinity and Attenuated Dephosphorylation
Calcium/Calmodulin Dependent Protein Kinase II Bound to NMDA Receptor 2B Subunit Exhibits Increased ATP Affinity and Attenuated Dephosphorylation
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DOI：
10.1371/journal.pone.0016495
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发表时间：
2011-03-15
期刊：
影响因子：
3.7
通讯作者：
Omkumar, Ramakrishnapillai V.
中科院分区：
文献类型：
--
作者：
Cheriyan, John;Kumar, Parimal;Omkumar, Ramakrishnapillai V.
钙/钙调蛋白依赖性蛋白激酶 II (CaMKII) 在学习和记忆中发挥关键作用。 N-甲基-D-天冬氨酸受体 (NMDAR) 的 NR2B 亚基是突触后膜上 CaMKII 的高亲和力结合伴侣。 NR2B 与 CaMKII 的 T 位点结合并调节其催化作用。通过使用等温滴定量热法 (ITC) 的直接测量，我们发现 NR2B 结合导致 CaMKII 对 ATP gamma S（ATP 类似物）的亲和力增加约 11 倍。 ITC 数据也与 CaMKII 的有序结合机制一致，其中 ATP 首先结合催化位点，然后结合肽底物。我们还表明，当 NR2B 与 CaMKII 结合时，磷酸-Thr(286)-α-CaMKII 的去磷酸化会减弱。这有利于体外 CaMKII/磷酸酶缀合物系统中 CaMKII Thr(286) 自磷酸化状态的持续存在。总的来说，我们的数据表明，CaMKII 的 NR2B 结合态具有独特的生化特性，这有助于支持突触记忆的分子开关的有效运作。
Calcium/calmodulin dependent protein kinase II (CaMKII) is implicated to play a key role in learning and memory. NR2B subunit of N-methyl-D-aspartate receptor (NMDAR) is a high affinity binding partner of CaMKII at the postsynaptic membrane. NR2B binds to the T-site of CaMKII and modulates its catalysis. By direct measurement using isothermal titration calorimetry (ITC), we show that NR2B binding causes about 11 fold increase in the affinity of CaMKII for ATP gamma S, an analogue of ATP. ITC data is also consistent with an ordered binding mechanism for CaMKII with ATP binding the catalytic site first followed by peptide substrate. We also show that dephosphorylation of phospho-Thr(286)-alpha-CaMKII is attenuated when NR2B is bound to CaMKII. This favors the persistence of Thr(286) autophosphorylated state of CaMKII in a CaMKII/phosphatase conjugate system in vitro. Overall our data indicate that the NR2B- bound state of CaMKII attains unique biochemical properties which could help in the efficient functioning of the proposed molecular switch supporting synaptic memory.