Metal-Induced Conformational Changes of Human Metallothionein-2A: A Combined Theoretical and Experimental Study of Metal-Free and Partially Metalated Intermediates
Metal-Induced Conformational Changes of Human Metallothionein-2A: A Combined Theoretical and Experimental Study of Metal-Free and Partially Metalated Intermediates
复制标题
DOI：
10.1021/ja5047878
复制
发表时间：
2014-07-02
影响因子：
15
通讯作者：
Russell, David H.
中科院分区：
文献类型：
--
作者：
Chen, Shu-Hua;Chen, Liuxi;Russell, David H.
电喷雾离子迁移质谱（ESI IM-MS）和分子动力学（MD）模拟揭示了金属诱导的构象变化和人类金属硫蛋白-2A（MT）的金属化机制的新见解，这是一种内在无序的蛋白质。含有apoMT的溶液的ESI产生apoMT的多个电荷状态;在向溶液中添加Cd 2+之后，ESI产生一系列CdiMT（i = 1-7）产物离子（参见Chen等人，Anal. 2013，85，7826-33）。CdiMT（i = 0-7）离子的离子迁移率到达时间分布（ATD）揭示了离子构象的多样性。的离子迁移率数据清楚地表明，构象多样性apoMT和部分金属离子收敛到有序，紧凑的构象作为绑定的Cd 2+离子的数量增加。MD模拟提供了关于CdiMT（i = 0-7）的构象候选物的额外信息，其支持不同构象群体在金属结合时的收敛。整合的IM-MS和MD数据提供了一个全局视图，显示逐步的构象转变的合奏作为金属离子结合的函数。ApoMT是由广泛的构象状态之间的球状紧凑和线圈丰富的扩展构象填充。在初始逐步金属添加期间（结合的金属离子的数量i = 1-3），金属离子结合到不同的位点以产生不同的构象，而对于i > 4，构象变化似乎是结构域特异性的，归因于β结构域的不同程度的无序; β结构域随着添加额外的金属离子而变得更加有序，促进向哑铃形构象的收敛。
Electrospray ionization ion mobility mass spectrometry (ESI IM-MS) and molecular dynamics (MD) simulations reveal new insights into metal-induced conformational changes and the mechanism for metalation of human metallothionein-2A (MT), an intrinsically disordered protein. ESI of solutions containing apoMT yields multiple charge states of apoMT; following addition of Cd2+ to the solution, ESI yields a range of CdiMT (i = 1-7) product ions (see Chen et al. Anal. Chem. 2013, 85, 7826-33). Ion mobility arrival-time distributions (ATDs) for the CdiMT (i = 0-7) ions reveal a diverse population of ion conformations. The ion mobility data clearly show that the conformational diversity for apoMT and partially metalated ions converges toward ordered, compact conformations as the number of bound Cd2+ ions increase. MD simulations provide additional information on conformation candidates of CdiMT (i = 0-7) that supports the convergence of distinct conformational populations upon metal binding. Integrating the IM-MS and MD data provides a global view that shows stepwise conformational transition of an ensemble as a function of metal ion bound. ApoMT is comprised of a wide range of conformational states that populate between globular-like compact and coil-rich extended conformations. During the initial stepwise metal addition (number of metal ions bound i = 1-3), the metal ions bind to different sites to yield distinct conformations, whereas for i > 4, the conformational changes appear to be domain-specific, attributed to different degrees of disorder of the beta domain; the beta domain becomes more ordered as additional metal ions are added, promoting convergences to the dumbbell-shaped conformation.