Dimerization propensity of the β1-adrenergic receptor in lipid nanodiscs probed by DEER and single-molecule spectroscopies

• 成果类型: Article
• 署名作者: Kubatova, Nina; Schmidt, Thomas; Wang, Quan; Clore, G. Marius
• 署名单位: National Institutes of Health (NIH) - USA; NIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11671
• DOI: 10.1073/pnas.2519609122
• 发表日期: 2025-09-23
• 关键词: protein-coupled receptors; crystal-structure; rhodopsin; heterodimerization; cholesterol

摘要

G protein-coupled receptors (GPCRs) comprise a large class of membrane proteins that mediate cellular responses to a wide range of external signals and as such constitute major drug targets. While oligomerization has been shown to play a well-established role in modulating signaling for class C GPCRs (e.g., the glutamate and GABA receptors), the functional relevance of oligomerization for class A receptors, such as the beta(1)-adrenergic receptor (beta(1)AR), remains unclear. Here, we have examined the influence of the membrane mimetic environment on the dimerization propensity of beta(1)AR using a combination of pulsed Q-band double electron-electron resonance spectroscopy and single-molecule fluorescence brightness measurements in an Anti-Brownian Elektrokinetic trap. While beta(1)AR is predominantly monomeric in docecyl-beta-D-maltoside (DDM) micelles, reconstitution of beta(1)AR in lipid nanodiscs preferentially favors symmetric parallel dimers. Using nanodiscs of different diameters we observed a clear size-dependent increase in the dimer fraction, reaching over 50% of the beta(1)AR molecules in large (similar to 12.5 nm diameter) nanodiscs. Addition of cholesteryl hemisuccinate, an analog of cholesterol, suppresses beta(1)AR dimerization in lipid nanodiscs, recapitulating the behavior in DDM micelles. This work provides quantitative evidence that beta(1)AR possesses an intrinsic, membrane sensitive predisposition for dimerization, and highlights the importance of spatial membrane constraints in the modulation of class A GPCR dimerization.