title: Cholesterol modulates the dimer interface of the β₂-adrenergic receptor via cholesterol occupancy sites.
abstract: The β2-adrenergic receptor is an important member of the G-protein-coupled receptor (GPCR) superfamily, whose stability and function are modulated by membrane cholesterol. The recent high-resolution crystal structure of the β2-adrenergic receptor revealed the presence of possible cholesterol-binding sites in the receptor. However, the functional relevance of cholesterol binding to the receptor remains unexplored. We used MARTINI coarse-grained molecular-dynamics simulations to explore dimerization of the β2-adrenergic receptor in lipid bilayers containing cholesterol. A novel (to our knowledge) aspect of our results is that receptor dimerization is modulated by membrane cholesterol. We show that cholesterol binds to transmembrane helix IV, and cholesterol occupancy at this site restricts its involvement at the dimer interface. With increasing cholesterol concentration, an increased presence of transmembrane helices I and II, but a reduced presence of transmembrane helix IV, is observed at the dimer interface. To our knowledge, this study is one of the first to explore the correlation between cholesterol occupancy and GPCR organization. Our results indicate that dimer plasticity is relevant not just as an organizational principle but also as a subtle regulatory principle for GPCR function. We believe these results constitute an important step toward designing better drugs for GPCR dimer targets.
authors.affiliation: CSIR-National Chemical Laboratory, Pune, India.
authors.forename: Xavier
authors.initials: X
authors.lastname: Prasanna
authors.affiliation: CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: amit@ccmb.res.in.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Chattopadhyay
authors.affiliation: CSIR-National Chemical Laboratory, Pune, India. Electronic address: d.sengupta@ncl.res.in.
authors.forename: Durba
authors.initials: D
authors.lastname: Sengupta
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011485:Protein Binding; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry* / Q000378:metabolism
chemical_list: D018343:Receptors, Adrenergic, beta-2; D002784:Cholesterol