Conformational heterogeneity of the aspartate transporter GltPh
Conformational heterogeneity of the aspartate transporter GltPh
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DOI：
10.1038/nsmb.2471
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发表时间：
2013-02-01
影响因子：
16.8
通讯作者：
Slotboom, Dirk Jan
中科院分区：
文献类型：
--
作者：
Hanelt, Inga;Wunnicke, Dorith;Slotboom, Dirk Jan
Glt（Ph）是属于谷氨酸转运蛋白家族的Pyrococcus horikoshii同源三聚体Na+偶联天冬氨酸转运蛋白。每个原聚体由参与亚基相互作用的三聚化结构域和具有底物结合位点的转运结构域组成。在这里，我们已经研究了构象变化的基础上运输Gltph使用[PR光谱。三聚化结构域形成刚性支架，而转运结构域采样多种构象，与转运周期期间的大规模运动一致。底物的结合改变了不同构象状态的占位性，但结构域仍然是异质性的。膜环境有利于构象不同的洗涤剂胶束中观察到的，但运输域仍然在两种环境中的结构异质性。我们的结论是，运输域样品的多个构象状态与大量占用的基板和耦合离子的存在下，与所观察到的转运蛋白构象之间的平衡常数接近统一一致。
Glt(Ph) is a Pyrococcus horikoshii homotrimeric Na+-coupled aspartate transporter that belongs to the glutamate transporter family. Each protomer consists of a trimerization domain involved in subunit interaction and a transporting domain with the substrate-binding site. Here, we have studied the conformational changes underlying transport by Gltph using [PR spectroscopy. The trimerization domains form a rigid scaffold, whereas the transporting domains sample multiple conformations, consistent with large-scale movements during the transport cycle. Binding of substrates changed the occupancies of the different conformational states, but the domains remained heterogeneous. The membrane environment favored conformations different from those observed in detergent micelles, but the transporting domain remained structurally heterogeneous in both environments. We conclude that the transporting domains sample multiple conformational states with substantial occupancy regardless of the presence of substrate and coupling ions, consistent with equilibrium constants close to unity between the observed transporter conformations.