Odorant-binding proteins (OBPs) facilitate olfactory perception by binding and transporting hydrophobic ligands, including lipids, in insect systems. OBP44a protein from Drosophila melanogaster acts as a fatty-acid-binding protein (FABP) to regulate lipid storage and is involved in brain development. In this study, we explore the interaction of OBP44a, with various lipid molecules to elucidate structural changes that occur upon binding to membranes. We chose a vesicle system to mimic membrane-protein interaction. Using nuclear magnetic resonance (NMR) spectroscopy, we determined contact sites of OBP with vesicles upon binding different lipids at varying pH values. Our study investigates the interactions of OBP44a and its mutants with lipid vesicles. NMR paramagnetic relaxation enhancement (PRE) experiments with paramagnetic doped vesicles, suggest membrane interactions at specific sites on the protein. These are also sites undergoing changes with fatty acid binding. Residue substitutions in these sites can modulate the vesicle contacts. These findings provide insights into the pH-sensitive nature of OBP44-lipid interactions with vesicles and how that interaction can be coupled with fatty acid binding. Current study aims to offer insights into the molecular basis of OBP44a and its role in lipid delivery. This study contributes to a deeper understanding of OBP function and their broader relevance in lipid-mediated processes.
Puja et al. (Sun,) studied this question.