Stabilization versus flexibility: detergent-dependent trade-offs in neurotensin receptor 1 GPCR ensembles

Abstract

Detergents provide essential membrane-mimetic environments for studying G protein-coupled receptors (GPCRs), but their molecular impact on receptor energetics remains incompletely understood. We combined ligand binding, thermostability measurements and atomistic molecular dynamics to dissect detergent- versus ligand-driven stabilization in a thermostabilized neurotensin receptor 1 (enNTS1). Circular dichroism and ligand binding assays revealed that apo enNTS1 becomes progressively more stable in decyl maltoside (DM), dodecyl maltoside (DDM), and lauryl maltose neopentyl glycol (LMNG). Yet this gain in baseline stability was accompanied by a paradox: LMNG, the most stabilizing detergent, supported the weakest neurotensin agonist binding affinity. Thermodynamic analysis resolved this contradiction by partitioning stability into detergent-driven conformational rigidity ({Delta}Gconf) and ligand-induced stabilization ({Delta}Gligand). In DM, {Delta}Gligand contributions were large, consistent with the receptors engineered background. In contrast, LMNG maximized {Delta}Gconf, constraining conformational flexibility and reducing {Delta}Gligand. Molecular dynamics simulations corroborated these results, showing that LMNG formed denser, less mobile detergent shells around the receptor, enhancing protein-detergent interaction energies while limiting conformational flexibility. Redistribution of ligand contacts, particularly at neurotensin residue Y11, further underscored detergent-dependent modulation of the binding pocket. These results highlight a fundamental trade-off: LMNG provides exceptional receptor stabilization, supporting structural studies, but may mask conformational states relevant to signaling. In contrast, less rigid detergents preserve ligand-induced transitions at the expense of stability. These findings emphasize that detergent choice should be guided by whether the goal is structural resolution or dynamic characterization.