Crystal structure of MalK, the ATPase subunit of the trehalose/maltose ABC transporter of the archaeon Thermococcus litoralis
Crystal structure of MalK, the ATPase subunit of the trehalose/maltose ABC transporter of the archaeon Thermococcus litoralis
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DOI：
10.1093/emboj/19.22.5951
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发表时间：
2000-11-15
期刊：
影响因子：
11.4
通讯作者：
Welte, W
中科院分区：
文献类型：
--
作者：
Diederichs, K;Diez, J;Welte, W
ABC转运蛋白家族的成员将各种各样的分子运送进或运出细胞和细胞室。除了一个转位孔外，每个成员都有两个相似的核苷三磷酸结合亚单位或结构域，以便将供能反应与运输结合起来。在几种革兰氏阴性菌和古生菌的麦芽糖转运体中，核苷三磷酸结合亚单位含有一个C末端调节域。亚基的二聚体以细胞质的形式连接到易位孔上。在这里，我们报告了这种二聚体的晶体结构，在1.9埃分辨率下显示了两个结合的焦磷酸盐分子。二聚体由ATPase结构域结合而成，两个调节域连接在相反的极性上。在二聚体的界面和与易位孔接触的残基对应的区域中，观察到明显偏离2倍对称性。根据已知的同源大肠杆菌和鼠伤寒沙门氏菌蛋白的突变，对其结构及其与功能的关系进行了讨论。
The members of the ABC transporter family transport a wide variety of molecules into or out of cells and cellular compartments. Apart from a translocation pore, each member possesses two similar nucleoside triphosphate-binding subunits or domains in order to couple the energy-providing reaction with transport. In the maltose transporter of several Gram-negative bacteria and the archaeon Thermococcus litoralis, the nucleoside triphosphate-binding subunit contains a C-terminal regulatory domain. A dimer of the subunit is attached cytoplasmically to the translocation pore. Here we report the crystal structure of this dimer showing two bound pyrophosphate molecules at 1.9 Angstrom resolution. The dimer forms by association of the ATPase domains, with the two regulatory domains attached at opposite poles. Significant deviation from 2-fold symmetry is seen at the interface of the dimer and in the regions corresponding to those residues known to be in contact with the translocation pore. The structure and its relationship to function are discussed in the light of known mutations from the homologous Escherichia coli and Salmonella typhimurium proteins.