An Adaptable Phospholipid Membrane Mimetic System for Solution NMR Studies of Membrane Proteins.

Abstract

Based on the saposin-A (SapA) scaffold protein we demonstrate the suitability of a size-adaptable phospholipid membrane-mimetic system for solution NMR studies of membrane proteins under close-to-native conditions. The Salipro nanoparticle size can be tuned over a wide pH range by adjusting the saposin-to-lipid stoichiometry enabling maintenance of sufficiently high amounts of phospholipid in the Salipro nanoparticle to mimic a realistic membrane environment while controlling the overall size to enable solution NMR for a range of membrane proteins. Three representative membrane proteins including one G-protein-coupled receptor (GPCR) were successfully incorporated into SapA-dimyristoylphosphatidylcholine (DMPC) nanoparticles and studied by solution NMR spectroscopy.