Biophysical characterization dataset of native nicotinic acetylcholine receptor in lipid-like detergent complexes.

Abstract

For a long time, traditional purification and extraction methods for the native Torpedo californica nicotinic acetylcholine receptor in lipid-like detergent complex (nAChR-DC) have compromised its purity, functionality and X-ray structural studies possibility. The dataset presented in this article provide a characterization of the Torpedo californica nAChR-DC purified using a sequential purification processes developed in our laboratory [1]. This purification takes in consideration all of the physicochemical and functional requirements stablished by several researchers for the past three decades for the nAChR. These requirements were addressed in order to preserve the stability and functionality of nAChR-DC while ensuring the highest degree of protein purity. We focused on the effect of cholesteryl hemisuccinate (CHS) supplementation on nAChR conformational changes during the purification process. Data from the size exclusion chromatography of the nAChR-DC supplemented with CHS in concentrations ranging from 0.01 mM, 0.1 mM, 0.2 mM and 0.5 mM consistently demonstrated that 0.5 mM CHS affects receptor stability via disassemble of the pentameric oligomer. However, 0.2 mM CHS produced negligible nAChR-DC subunit disruption.The purified nAChR-DC has been characterized by circular dichroism (CD) and fluorescence recovery after photobleaching (FRAP), in order to assess its stability. The CD data was recorded in the wavelength range of 190-250 nm, showed that CHS induce a ⍺-helix to β-sheet transition of the nAChR-DC. The nAChR-LFC-16 delipidation with Methyl-β-Cyclodextrin decreased the percentage of α-helix and increased the β-sheet antiparallel secondary structure and levels the percentage of turns to that of the nAChR-DC without CHS treatment. Additionally, the stability of the nAChR-DC supplemented with CHS and incorporated into lipid cubic phase (LCP) was monitored for a period of 30 days by means of FRAP. The LCP-FRAP data allowed to establish possible optimal crystallization conditions for the development of crystals from purified nAChR-conjugated to α-Bungarotoxin, Alexa Fluor ™ 488 (α-BTX) in order to obtain a high-resolution atomic structure by X-ray diffraction.