Promiscuous binding of ligands by β-lactoglobulin involves hydrophobic interactions and plasticity
Promiscuous binding of ligands by β-lactoglobulin involves hydrophobic interactions and plasticity
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DOI：
10.1016/j.jmb.2007.01.077
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发表时间：
2007-04-20
影响因子：
5.6
通讯作者：
Goto, Yuji
中科院分区：
文献类型：
--
作者：
Konuma, Tsuyoshi;Sakurai, Kazumasa;Goto, Yuji
牛乳球蛋白（β LG）结合各种疏水配体，但具体如何结合尚不清楚。为了了解这种混杂的结合的结构基础，我们研究了β LG与棕榈酸（PA）的相互作用，使用heterophylline NMR光谱。使用色氨酸荧光监测滴定，并且HSQC光谱证实PA-β LG复合物的1：1化学计量。在PA的结合，信号消失和大的化学位移的变化被观察到的残基位于入口和底部的空腔，分别。这一观察结果表明，下部区域与PA形成刚性连接，而入口更灵活。这一结果与PA与肠脂肪酸结合蛋白的结合形成对比，肠脂肪酸结合蛋白是萼素超家族的另一个成员，其中在配体结合后发生结构巩固。另一方面，β LG容纳各种疏水配体的能力类似于GroEL，其中大的疏水腔和柔性结合位点赋予结合各种疏水底物的能力。考虑到这些观察结果，有人建议，除了疏水腔的存在下，入口区域的可塑性使得各种形状的疏水配体的结合成为可能。因此，与许多酶的特异性结合相反，β LG提供了一个低特异性但高亲和力结合的例子，这可能在蛋白质-配体和蛋白质-蛋白质网络中发挥重要作用。(c)2007爱思唯尔有限公司保留所有权利。
Bovine-lactoglobulin (beta LG) binds a variety of hydrophobic ligands, though precisely how is not clear. To understand the structural basis of this promiscuous binding, we studied the-interaction of beta LG with palmitic acid (PA) using heteronuclear NMR spectroscopy. The titration was monitored using tryptophan fluorescence and a HSQC spectrum confirmed a 1:1 stoichiometry for the PA-beta LG complex. Upon the binding of PA, signal disappearances and large changes in chemical shifts were observed for the residues located at the entrance and bottom of the cavity, respectively. This observation indicates that the lower region makes a rigid connection with PA whereas the entrance is more flexible. The result is in contrast to the binding of PA to intestinal fatty acid-binding protein, another member of the calycin superfamily, in which structural consolidation occurs upon ligand binding. On the other hand, the ability of beta LG to accommodate various hydrophobic ligands resembles that of GroEL, in which a large hydrophobic cavity and flexible binding site confer the ability to bind various hydrophobic substrates. Considering these observations, it is suggested that, in addition to the presence of the hydrophobic cavity, the plasticity of the entrance region makes possible the binding of hydrophobic ligands of various shapes. Thus, in contrast to the specific binding seen for many enzymes, beta LG provides an example of binding with low specificity but high affinity, which may play an important role in protein-ligand and protein-protein networks. (c) 2007 Elsevier Ltd. All rights reserved.