Crystal structure of a catalytic intermediate of the maltose transporter
Crystal structure of a catalytic intermediate of the maltose transporter
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DOI：
10.1038/nature06264
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发表时间：
2007-11-22
期刊：
影响因子：
64.8
通讯作者：
Chen, Jue
中科院分区：
文献类型：
--
作者：
Oldham, Michael L.;Khare, Dheeraj;Chen, Jue
大肠杆菌的麦芽糖摄取系统是ATP结合盒式转运蛋白超级家族的良好特征成员。在这里，我们介绍了与麦芽糖结合蛋白，麦芽糖和ATP复合物中完整麦芽糖转运蛋白的2.8-Angstrom晶体结构。这种结构通过阻止ATP水解的突变稳定，可在封闭的，结合的ATP结合构象中捕获ATP结合盒二聚体。麦芽糖在两个跨膜亚基的界面的充满溶剂的腔中被阻塞，约一半进入脂质双层。结合蛋白在开放的构象中停靠在空腔的入口处，并用作帽，以确保糖分子的单向易位。这些结果为转运机制提供了直接的证据，当盒式二聚体关闭到水解ATP时，将溶质从结合蛋白转移到跨膜亚基。
The maltose uptake system of Escherichia coli is a well-characterized member of the ATP-binding cassette transporter superfamily. Here we present the 2.8-angstrom crystal structure of the intact maltose transporter in complex with the maltose-binding protein, maltose and ATP. This structure, stabilized by a mutation that prevents ATP hydrolysis, captures the ATP-binding cassette dimer in a closed, ATP-bound conformation. Maltose is occluded within a solvent-filled cavity at the interface of the two transmembrane subunits, about halfway into the lipid bilayer. The binding protein docks onto the entrance of the cavity in an open conformation and serves as a cap to ensure unidirectional translocation of the sugar molecule. These results provide direct evidence for a concerted mechanism of transport in which solute is transferred from the binding protein to the transmembrane subunits when the cassette dimer closes to hydrolyse ATP.