Real time ligand-induced motion mappings of AChBP and nAChR using X-ray single molecule tracking

Abstract

We observed the dynamic three-dimensional (3D) single molecule behaviour of acetylcholine-binding protein (AChBP) and nicotinic acetylcholine receptor (nAChR) using a single molecule tracking technique, diffracted X-ray tracking (DXT) with atomic scale and 100 Π1/4s time resolution. We found that the combined tilting and twisting motions of the proteins were enhanced upon acetylcholine (ACh) binding. We present the internal motion maps of AChBP and nAChR in the presence of either ACh or α -bungarotoxin (α Btx), with views from two rotational axes. Our findings indicate that specific motion patterns represented as biaxial angular motion maps are associated with channel function in real time and on an atomic scale.