The ligand-mediated affinity of brain-type fatty acid-binding protein for membranes determines the directionality of lipophilic cargo transport

Publication date: Available online 9 August 2019Source: Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of LipidsAuthor(s): Yi-Yun Cheng, Yun-Fang Huang, Hsin-Hui Lin, Wun-Shaing Wayne Chang, Ping-Chiang LyuAbstractThe intracellular transport of lipophilic cargoes is a highly dynamic process. In eukaryotic cells, the uptake and release of long-chain fatty acids (LCFAs) are executed by fatty-acid binding proteins. However, how these carriers control the directionality of cargo trafficking remains unclear. Here, we revealed that the unliganded archetypal Drosophila brain-type fatty acid-binding protein (dFABP) possesses a stronger binding affinity than its liganded counterpart for empty nanodiscs (ND). Titrating unliganded dFABP and nanodiscs with LCFAs rescued the broadening of FABP cross-peak intensities in HSQC spectra from a weakened protein–membrane interaction. Two out of the 3 strongest LCFA contacting residues in dFABP identified by NMR HSQC chemical shift perturbation (CSP) are also part of the 30 ND-contacting residues (out of the total 130 residues in dFABP), revealed by attenuated TROSY signal in the presence of lipid ND to apo-like dFABP. Our crystallographic temperature factor data suggest enhanced αII helix dynamics upon LCFA binding, compensating for the entropic loss in the βC-D/βE-F loops. The aliphatic tail of bound LCFA impedes the charge-charge interaction between dFABP and the head groups of the membrane, and dFABP is prone to dissoci...
Source: Biochimica et Biophysica Acta (BBA) Molecular and Cell Biology of Lipids - Category: Lipidology Source Type: research