title: The human liver fatty acid binding protein T94A variant alters the structure, stability, and interaction with fibrates.
abstract: Although the human liver fatty acid binding protein (L-FABP) T94A variant arises from the most commonly occurring single-nucleotide polymorphism in the entire FABP family, there is a complete lack of understanding regarding the role of this polymorphism in human disease. It has been hypothesized that the T94A substitution results in the complete loss of ligand binding ability and function analogous to that seen with L-FABP gene ablation. This possibility was addressed using the recombinant human wild-type (WT) T94T and T94A variant L-FABP and cultured primary human hepatocytes. Nonconservative replacement of the medium-sized, polar, uncharged T residue with a smaller, nonpolar, aliphatic A residue at position 94 of the human L-FABP significantly increased the L-FABP α-helical structure content at the expense of β-sheet content and concomitantly decreased the thermal stability. T94A did not alter the binding affinities for peroxisome proliferator-activated receptor α (PPARα) agonist ligands (phytanic acid, fenofibrate, and fenofibric acid). While T94A did not alter the impact of phytanic acid and only slightly altered that of fenofibrate on the human L-FABP secondary structure, the active metabolite fenofibric acid altered the T94A secondary structure much more than that of the WT T94T L-FABP. Finally, in cultured primary human hepatocytes, the T94A variant exhibited a significantly reduced extent of fibrate-mediated induction of PPARα-regulated proteins such as L-FABP, FATP5, and PPARα itself. Thus, while the T94A substitution did not alter the affinity of the human L-FABP for PPARα agonist ligands, it significantly altered the human L-FABP structure, stability, and conformational and functional response to fibrate.
authors.affiliation: Department of Physiology and Pharmacology, Texas A&M University , TVMC, College Station, Texas 77843-4466, United States.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Martin
authors.forename: Avery L
authors.initials: AL
authors.lastname: McIntosh
authors.forename: Huan
authors.initials: H
authors.lastname: Huang
authors.forename: Shipra
authors.initials: S
authors.lastname: Gupta
authors.forename: Barbara P
authors.initials: BP
authors.lastname: Atshaves
authors.forename: Kerstin K
authors.initials: KK
authors.lastname: Landrock
authors.forename: Danilo
authors.initials: D
authors.lastname: Landrock
authors.forename: Ann B
authors.initials: AB
authors.lastname: Kier
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Schroeder
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D050612:Fatty Acid Transport Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins / Q000819:agonists / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011345:Fenofibrate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D058607:Fibric Acids / Q000378:metabolism / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006358:Hot Temperature; D006801:Humans; D000960:Hypolipidemic Agents / Q000378:metabolism / Q000494:pharmacology*; D008024:Ligands; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D047493:PPAR alpha / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D010831:Phytanic Acid / Q000378:metabolism / Q000494:pharmacology; D020641:Polymorphism, Single Nucleotide; D055550:Protein Stability; D017433:Protein Structure, Secondary; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: C493319:FABP1 protein, human; D050612:Fatty Acid Transport Proteins; D050556:Fatty Acid-Binding Proteins; D058607:Fibric Acids; D000960:Hypolipidemic Agents; D008024:Ligands; D047493:PPAR alpha; D011994:Recombinant Proteins; C484819:SLC27A5 protein, human; D010831:Phytanic Acid; C006012:fenofibric acid; D011345:Fenofibrate