Molecular Neurobiology Division, Rajiv Gandhi Centre For Biotechnology, Thycaud, P. O., Thiruvananthapuram, 695014, India; Research scholar, University of Kerala, India.
Molecular Neurobiology Division, Rajiv Gandhi Centre For Biotechnology, Thycaud, P. O., Thiruvananthapuram, 695014, India; Research scholar, Manipal Academy of Higher Education, Manipal, 576 104, India.
Arch Biochem Biophys. 2020 May 30;685:108348. doi: 10.1016/j.abb.2020.108348. Epub 2020 Mar 18.
Memory formation transpires to be by activation and persistent modification of synapses. A chain of biochemical events accompany synaptic activation and culminate in memory formation. These biochemical events are steered by interplay and modulation of various synaptic proteins, achieved by conformational changes and phosphorylation/dephosphorylation of these proteins. Calcium/calmodulin dependent protein kinase II (CaMKII) and N-methyl-d-aspartate receptors (NMDARs) are synaptic proteins whose interactions play a pivotal role in learning and memory process. Catalytic activity of CaMKII is modulated upon its interaction with the GluN2B subunit of NMDAR. The structural basis of this interaction is not clearly understood. We have investigated the role of Glu of α-CaMKII, a conserved residue present in the ATP binding region of kinases, in the regulation of catalysis of CaMKII by GluN2B. Mutation of Glu to Gly exerts different effects on the kinetic parameters of phosphorylation of GluN2B and GluN2A, of which only GluN2B binds to the T-site of CaMKII. GluN2B induced modulation of the kinetic parameters of peptide substrate was altered in the E60G mutant. The mutation almost abolished the modulation of the apparent K value for protein substrate. However, although kinetic parameters for ATP were altered by mutating Glu, modulation of the apparent K value for ATP by GluN2B seen in WT was exhibited by the E60G mutant of α-CaMKII. Hence our results posit that the communication of the T-site of CaMKII with protein substrate binding region of active site is mediated through Glu while the communication of the T-site with the ATP binding region is not entirely dependent on Glu.
记忆的形成是通过突触的激活和持续修饰来实现的。一系列生化事件伴随着突触的激活，并最终导致记忆的形成。这些生化事件是由各种突触蛋白的相互作用和调节来控制的，通过这些蛋白质的构象变化和磷酸化/去磷酸化来实现。钙/钙调蛋白依赖性蛋白激酶 II（CaMKII）和 N-甲基-D-天冬氨酸受体（NMDAR）是突触蛋白，它们的相互作用在学习和记忆过程中起着关键作用。CaMKII 的催化活性在与 NMDAR 的 GluN2B 亚基相互作用时被调节。这种相互作用的结构基础尚不清楚。我们研究了α-CaMKII 的 Glu 的作用，α-CaMKII 是激酶的 ATP 结合区域中存在的保守残基，它调节 CaMKII 与 GluN2B 的催化作用。Glu 突变为 Gly 对 GluN2B 和 GluN2A 的磷酸化动力学参数产生不同的影响，其中只有 GluN2B 与 CaMKII 的 T 位结合。GluN2B 诱导的肽底物动力学参数的调节在 E60G 突变体中发生改变。该突变几乎消除了对蛋白底物表观 K 值的调节。然而，尽管通过突变 Glu 改变了 ATP 的动力学参数，但在 WT 中观察到的由 GluN2B 对 ATP 的表观 K 值的调节，在α-CaMKII 的 E60G 突变体中也表现出来。因此，我们的结果表明，CaMKII 的 T 位与活性位点的蛋白底物结合区域的通讯是通过 Glu 介导的，而 T 位与 ATP 结合区域的通讯并不完全依赖于 Glu。
