Liu Tao, Chen Fangjin, Tang Ning, Feng Jiannan, Zhao Dongsheng, Wei Kaihua, Zhu Yunping, He Fuchu, Liu Shaojun
State Key Laboratory of Proteomics, Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, PR China.
J Mol Recognit. 2009 May-Jun;22(3):205-14. doi: 10.1002/jmr.933.
On T cell receptor (TCR) stimulation, src homology 2 domain-containing transforming protein C1 (SHC1) had been found to bind the tyrosine-phosphorylated CD247 chain of the receptor via its src homology 2 (SH2) domain, delivering signals that control T cell development and activation. However, how the phosphorylation of CD247 led to the instant binding has not been characterized clearly. To study the binding process in detail, we simulated and compared the interaction processes of the SH2 domain with CD247 and phosphorylated CD247, respectively. Unexpectedly, the simulation revealed that SHC1 can also bind the nonphosphorylated CD247 peptide, which was further validated to be a weak binding by affinity pull-down experiment. The molecular dynamics (MD) simulation also revealed that the CD247 peptide formed a folding conformation with its Leu209 inserted into the hydrophobic binding pocket in SHC1. And on phosphorylation, it was the electrostatic attraction between the CD247 Tyr(P)206 and the SHC1 Tyr(P)-binding pocket that destroyed the folding conformation of the nonphosphorylated CD247 and, aided by the electrostatic attraction between SHC1 and the Asp203 of CD247, led to the extended conformation of the phosphorylated CD247 binding to SHC1 strongly. The results suggest that nonphosphorylated CD247 can recruit SHC1 in advance to prepare for the instant needs for SHC1 on TCR stimulation. In view of the ubiquity of phosphorylation in protein interaction regulation, we think this study also exemplified the usefulness of MD in more interactome research involving phosphorylation.
在T细胞受体（TCR）受到刺激时，已发现含src同源2结构域的转化蛋白C1（SHC1）通过其src同源2（SH2）结构域与受体的酪氨酸磷酸化CD247链结合，传递控制T细胞发育和激活的信号。然而，CD247的磷酸化如何导致即时结合尚未明确表征。为了详细研究结合过程，我们分别模拟并比较了SH2结构域与CD247以及磷酸化CD247的相互作用过程。出乎意料的是，模拟显示SHC1也能结合未磷酸化的CD247肽，亲和下拉实验进一步验证这是一种弱结合。分子动力学（MD）模拟还显示，CD247肽形成了一种折叠构象，其Leu209插入到SHC1的疏水结合口袋中。磷酸化时，是CD247 Tyr(P)206与SHC1 Tyr(P)结合口袋之间的静电吸引力破坏了未磷酸化CD247的折叠构象，并在SHC1与CD247的Asp203之间的静电吸引力辅助下，导致磷酸化CD247以伸展构象与SHC1强烈结合。结果表明，未磷酸化的CD247可以预先招募SHC1，为TCR刺激时对SHC1的即时需求做好准备。鉴于磷酸化在蛋白质相互作用调节中的普遍性，我们认为这项研究也例证了MD在更多涉及磷酸化的相互作用组研究中的有用性。
