Interaction of perfluoroalkyl acids with human liver fatty acid-binding protein
Interaction of perfluoroalkyl acids with human liver fatty acid-binding protein
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DOI：
10.1007/s00204-014-1391-7
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发表时间：
2016-01-01
影响因子：
6.1
通讯作者：
Dai, Jiayin
中科院分区：
文献类型：
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作者：
Sheng, Nan;Li, Juan;Dai, Jiayin
全氟烷基酸具有高度持久性和生物累积性，因此在人类和环境中广泛分布。肝脏是PFAAs的重要靶点，但PFAAs与肝细胞蛋白相互作用的机制仍知之甚少。我们的特点是结合PFAAs的人肝脂肪酸结合蛋白（hL-FABP），并确定其相互作用的关键结构特征。采用荧光位移法和等温滴定量热法（ITC）研究了PFAAs与hL-FABP的结合作用。进行分子模拟以确定结合位点处的相互作用。ITC测定结果显示，当PFOA/PFNA摩尔比为1：1时，对hL-FABP的亲和力适中，对PFHxS的亲和力较弱，对PFHxA无亲和力。此外，相互作用主要是通过静电吸引和氢键介导的。用Asp取代Asn 111导致对PFAA的结合亲和力丧失，表明其对初始PFAA与外部结合位点结合的关键作用。Arg 122被Gly取代后，PFAA仅与一个分子的hL-FABP结合。分子模拟结果表明，Arg 122的取代增加了PFOA的外结合口袋的体积，使其不能与PFOA形成密集的疏水堆积和氢键，并突出了其在结合过程中的关键作用。PFAAs的结合亲和力随碳原子数的增加而显著增加。Arg 122和Asn 111在这些相互作用中发挥了关键作用。我们的研究结果可能有助于了解PFAAs在人体中的分布模式，生物累积，消除和毒性。
Perfluoroalkyl acids (PFAAs) are highly persistent and bioaccumulative, resulting in their broad distribution in humans and the environment. The liver is an important target for PFAAs, but the mechanisms behind PFAAs interaction with hepatocyte proteins remain poorly understood. We characterized the binding of PFAAs to human liver fatty acid-binding protein (hL-FABP) and identified critical structural features in their interaction. The binding interaction of PFAAs with hL-FABP was determined by fluorescence displacement and isothermal titration calorimetry (ITC) assay. Molecular simulation was conducted to define interactions at the binding sites. ITC measurement revealed that PFOA/PFNA displayed a moderate affinity for hL-FABP at a 1: 1 molar ratio, a weak binding affinity for PFHxS and no binding for PFHxA. Moreover, the interaction was mainly mediated by electrostatic attraction and hydrogen bonding. Substitution of Asn111 with Asp caused loss of binding affinity to PFAA, indicating its crucial role for the initial PFAA binding to the outer binding site. Substitution of Arg122 with Gly caused only one molecule of PFAA to bind to hL-FABP. Molecular simulation showed that substitution of Arg122 increased the volume of the outer binding pocket, making it impossible to form intensive hydrophobic stacking and hydrogen bonds with PFOA, and highlighting its crucial role in the binding process. The binding affinity of PFAAs increased significantly with their carbon number. Arg122 and Asn111 played a pivotal role in these interactions. Our findings may help understand the distribution pattern, bioaccumulation, elimination, and toxicity of PFAAs in humans.