Brain fatty acid binding protein exhibits non-preferential and mutation-resistant binding towards fatty acids

Abstract

Members of the fatty acid binding protein (FABP) family function as intracellular transporters of long chain fatty acids and other hydrophobic molecules to different cellular compartments. Brain fatty acid binding protein (FABP7) exhibits ligand-directed differences in cellular transport behavior. For example, when FABP7 binds to docosahexaenoic acid (DHA), the complex relocates to the nucleus and influences transcriptional activity, whereas FABP7 bound with monosaturated fatty acids remain in the cytosol. We used a variety of biophysical techniques to enhance understanding of ligand-directed transport. Specifically, we examine how FABP7 binds to fatty acids, including saturated stearic acid (SA), monounsaturated oleic acid (OA), and polyunsaturated DHA. We find that at 37°C FABP7 has near equivalent binding affinities for the fatty acids, while at lower temperatures, FABP7 exhibits a preference for the unsaturated fatty acids. Therefore, nuclear localization of the FABP7-DHA complex cannot be explained by binding preferences. Using NMR spectroscopy and molecular dynamics simulations, we observe that DHA uniquely affects the portal region of FABP7, which could enhance the complex's nuclear localization. Mutations to purported critical binding residues (R126L and Y128F) have little effect on fatty acid binding, with molecular dynamics simulations revealing that the bound fatty acid can adopt binding poses that can accommodate the mutations.

Integrating animal experiments, mass spectrometry and network-based approach to reveal the sleep-improving effects of Ziziphi Spinosae Semen and γ-aminobutyric acid mixture

“…With the network-based ingredient screening model, we highlighted four major ingredients (GABA, stearic acid, tetradecanoic acid, and coumestrol) of ZSSG that might be able to regulate sleep quality. Taking stearic acid as an example, experimental research has demonstrated that this ingredient binds to FBAP7 [ 50 ]. FBAP7 knock-out mice displayed an increase in wake during the light phase, indicating that FBAP7 is required for normal sleep inhibition [ 51 ].…”

Integrating animal experiment, mass spectrometry and network-based approach to reveal the improving sleep quality of Ziziphi Spinosae Semen and γ-aminobutyric acid mixture

“…With the network-based ingredient screening model, we highlighted four major ingredients (GABA, stearic acid, tetradecanoic acid, and coumestrol) of ZSSG that might be able to regulate sleep quality. Taking stearic acid as an example, experimental research has demonstrated that this ingredient binds to FBAP7 [44]. FBAP7 knock-out mice displayed an increase in wake during the light phase, indicating that FBAP7 is required for normal sleep inhibition [45].…”