The active ring-like structure of SecA revealed by electron crystallography: Conformational change upon interaction with SecB
The active ring-like structure of SecA revealed by electron crystallography: Conformational change upon interaction with SecB
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电子晶体学揭示了 SecA 的活性环状结构：与 SecB 相互作用时的构象变化
DOI：
10.1016/j.jsb.2007.01.015
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发表时间：
2007-07-01
影响因子：
3
通讯作者：
Sui, Sen-Fang
中科院分区：
文献类型：
--
作者：
Chen, Yong;Tai, Phang C.;Sui, Sen-Fang
SecA是一种多功能蛋白，参与细菌中的蛋白质易位。SecA在膜上的结构与在溶液中相比发生了显著的变化，并伴随着功能的改变。我们先前报道了SecA在脂质层上形成一种新的环状结构，这可能构成前蛋白易位通道的一部分。在本工作中，二维结晶的大肠杆菌SecA的脂质单层进行揭示SecA的结构细节的脂质层，并探讨其功能。通过SecA与带负电荷的脂质分子的特异性相互作用，获得了由环状结构组成的二维晶体。二维投影图和三维重建显示SecA具有明显的开放通道样结构，其外径为7nm，内径为2nm，为SecA在形成部分转位通道中的重要性提供了结构证据。在将晶体转移到Secl3溶液中后，该孔结构发生改变，表明脂质特异性SecA结构具有SecB结合活性。该方法为研究SecA与膜上配体复合物的结构提供了一种很有前途的技术。(c)2007年爱思唯尔公司All rights reserved.
SecA is a multifunctional protein involved in protein translocation in bacteria. The structure of SecA on membrane is dramatically altered compared with that in solution, accompanying with functional changes. We previously reported the formation of a novel ring-like structure of SecA on lipid layers, which may constitute part of the preprotein translocation channel. In the present work, two-dimensional crystallization of Escherichia coli SecA on lipid monolayers was performed to reveal the structural details of SecA on lipid layers and to investigate its function. The 2D crystals composed of ring-like structures were obtained by specific interaction between SecA and negatively charged lipid. The 2D projection map and 3D reconstruction from negative stained 2D crystals exhibited a distinct open channel-like structure of SecA, with an outer diameter of 7nm and an inner diameter of 2nm, providing the structural evidence for SecA importance in forming the part of the translocation channel. This pore structure is altered after transferring crystals to the Secl3 solution, indicating that the lipid-specific SecA structure has the SecB binding activity. The strategy developed here provides a promising technique for studying structure of SecA complex with its ligand on membrane. (c) 2007 Elsevier Inc. All rights reserved.