Conformational changes of three periplasmic receptors for bacterial chemotaxis and transport: The maltose-, glucose/galactose- and ribose-binding proteins.
Conformational changes of three periplasmic receptors for bacterial chemotaxis and transport: The maltose-, glucose/galactose- and ribose-binding proteins.
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DOI：
10.1006/jmbi.1996.0645
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发表时间：
1996-11-29
影响因子：
5.6
通讯作者：
Mowbray, SL
中科院分区：
文献类型：
--
作者：
Shilton, BH;Flocco, MM;Mowbray, SL
对革兰氏阴性菌的麦芽糖、葡萄糖/半乳糖和核糖结合蛋白进行了小角X射线散射实验。所有被证明是单体，减少在配体binding.The的回旋半径得到的结果麦芽糖结合蛋白同意以及与晶体结构的剂量，配体结合，和开放，配体自由的蛋白质，这表明这些确实是在溶液中的主要形式。封闭形式通过蛋白质-糖相互作用稳定，而开放构象通过两个结构域之间的紧密接触稳定。由于封闭结构域之间的空间关系对于与趋化性和转运伴侣的相互作用最为重要，因此开放结构域的稳定性将有助于防止无配体分子干扰功能。散射结果还提供了证据，表明与葡萄糖/半乳糖和核糖结合蛋白的配体结合相关的大的构象变化发生，这两种变化是相似的。建模表明，开放的形式类似于在相关的亮氨酸和亮氨酸/异亮氨酸/缬氨酸结合蛋白中发现的那些，但与麦芽糖结合蛋白和相关的嘌呤阻遏物所观察到的那些不同。(C)1996年学术出版社
Small-angle X-ray scattering experiments were carried out for the maltose-, glucose/galactose- and ribose-binding proteins of Gram negative bacteria. All were shown to be monomers that decrease in radius of gyration on ligand binding.The results obtained for the maltose-binding protein agree well with crystal structures of the dosed, ligand-bound, and open, ligand-free protein, suggesting that these are indeed the primary forms in solution. The closed form is stabilized by protein-sugar interactions, while the open conformation is stabilized by close contacts between the two domains. Since it is the proper spacial relationship of the domains in the closed form that is most important for interaction with chemotaxis and transport partners, the stabilization of the open form would help keep ligand-free molecules from interfering in function.The scattering results also provide evidence that a large conformational change takes place in association with ligand binding to the glucose/galactose- and ribose-binding proteins, and that the two changes are similar. Modeling suggests that the open forms resemble those found in the related leucine and leucine/isoleucine/valine-binding proteins, but are different from those observed for the maltose-binding protein and the related purine repressor. (C) 1996 Academic Press Limited