title: Interaction of perfluoroalkyl acids with human liver fatty acid-binding protein.
abstract: 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.
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
authors.forename: Nan
authors.initials: N
authors.lastname: Sheng
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China. aqzhang@rees.ac.cn.
authors.forename: Aiqian
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China. daijy@ioz.ac.cn.
authors.forename: Jiayin
authors.initials: J
authors.lastname: Dai
mesh_terms: D001665:Binding Sites; D002151:Calorimetry; D002208:Caproates / Q000737:chemistry / Q000378:metabolism; D002210:Caprylates / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D050556:Fatty Acid-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005227:Fatty Acids; D005466:Fluorocarbons / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
chemical_list: D002208:Caproates; D002210:Caprylates; C493319:FABP1 protein, human; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D005466:Fluorocarbons; D011994:Recombinant Proteins; C101816:perfluoro-n-nonanoic acid; C023036:perfluorooctanoic acid; C479228:perfluorohexanoic acid
keywords: Human liver fatty acid-binding protein; Interaction; Isothermal titration calorimetry; Molecular simulation; Perfluorinated compounds